I think there are plenty of articles that have covered toxic people at the workplace, written by professionals who have way more experience and exposure than I.
I'll take a stab at this not because I want to add to the merriment of advice that's already out there, but to draw analogies between personal lives and working environments that overlap and remind my future (and your) self when times seem bad.
My first encounter with a toxic environment was when I've just graduated from JC and took a temp job at Woodlands industrial park as a sales admin assistant. 3 months felt like 3 years and I wanted to quit every day but my mother insisted I stayed on. My mum has always been about tough love but on some sadistic scale, it made my bullshit for nonsense a lot higher (which was her goal anyway). It was later, when my organisational behaviour lecturer introduced this idea of a "toxic work environment" that I started to have a frame around the experiences I was feeling.
Toxic bosses
There are tons of literature about dealing with bosses that take score. Bosses that are unreasonable and unsympathetic. Bosses that seem not to care, or give appreciation to what you are doing. Bosses that are bossy, passive aggressive, or worse, vindictive. Plenty of people's push factors are often their immediate supervisor. For those head-strong subordinates, they leave their jobs in self-preservation. Others resemble women (and men) in emotionally and physically abusive relationships. The individuals internalise the discourse and abuse hurled at them. After a while, you believe that you're not good enough, and that no other employer out there would want you because you're "so lousy". The worst cases are when these abused employees that never leave and start the abuse themselves when they stay long enough to be promoted.
Workplace abuse is a boo-boo topic at any HR office and an uncomfortable situation to be in. I often have a 3 month-rule. If the employer continues to attack your work quality personally, have enough self-love to leave and start fresh in mind with another employer.
("you are a graduate and you can't even handle simple admin"..."I don't want to see your face, you annoy me."...or nonverbals like neglect with old shoulders when confronted with an urgent request)
Victims of abuse tend to follow a path dependency especially when over time, this type of partner is all they know how to love. So sometimes it helps to have a critixal checklist of questions to uncomfortably ask your prospective employer so as to protect yourself. It helps to voice out your experiences with workplace abuse. It's not a sign of weakness and any prospective employer who thinks that way will probably not be suitable for you. Voice it in a way that empowers (I refuse to be treated with no dignity, did you know he said...) rather than come across as a complaint (she gave me too much work, I had to work until 2am) because the latter doesn't show that you know what you're doing. So, if you list down the reasons for leaving in a list and many of them sound like petty complaints, you know perhaps you should revist your working style instead.
Toxic colleagues
I have 2 personal beliefs. One, never work with friends, and second, never mix work with the personal.
It's one thing to invite your colleagues to a wedding or party, but another to reveal personable traits such as your person judgement on certain issues (or worse, even other colleagues as that would just be gossiping). It's okay to share general views and another to express something like, "I think BDSM is cool and everyone should try it." I never cross the blood-brain barrier of work life and personal life.
For one, what happens if you DO gossip about others, what makes you think they won't turn on you? Perhaps your follow-up thought would be, they'd gossip about me anyway, why shouldn't I join in to ensure I don't keep tabs on them?
Come on lah, if people really want to speak badly about you, you wouldn't know it and even if you do - what do you intend to do? Follow up and confront them about it? Then whole thing falls apart and you're stuck with 0 "friends" and 0 trust from those around you; and have to walk away licking your wounds.
Keep your record clean, above board, partake not in the toxicity of this high school gossip shit, and just shrug away comments that come your way that are meant to fish for a response. Make it about work all the time; joke about work and maybe Trump, but never sink into the quicksand of unhealthy finger pointing and judgement. Toxic colleagues will want lure you into their world, like a band of druggies and their gossip is veil false security, an addiction, that makes you feel that you're in-the-know. I'd rather have no "friends" at work, than companions like these.
Ultimately, in time, toxic cliques and groupies will drive away good colleagues and what is left is a pile of bones that will eventually be discarded. I've seen it happen twice now, and favouritism will be the downfall of any management or business. By the time it happens, I'll be frolicking with some dolphins off the Australian coast.
Toxic clients
I find that Singapore generally have this "maid-mentality". What do I mean by this?
They think that just because they pay someone, they own and get to dictate when domestic helpers shit, eat and sleep. They expect them to go "beyond their jobscope" to also help you clean their backside. Some clients do this all the time - this unhealthy relationship is what drives many account servicing people out of their jobs and into a mental institution.
It wears any person down. One drink, two, and suddenly you're saddled with a health problem brought about by the many recesses of "the pressures in life".
Recite this: I do not deserve to suffer for the pains of others.
And walk away.
Simple as that, anger and malice requires a dance partner, let the chilling hurtful words slide from your back, don't ever let the water enter and fuel that deep dark place of doubt and insecurity.
Fuck it, fuck off, fuck them. Politely of course.
If people with money (money that isn't even theirs) cannot learn to be proper human beings, then they can jollywell learn. If the good stay silent, the evil will win. Hasn't the holocaust or any genocide taught us enough already?
It is not about war, it is to take an active role in making the world a better place by taking small steps.
Eventually, as long as any toxic client makes it personal, when you're losing sleep not because you can't bring in the deliverables for them but because they spite your very being, it's time to grow a backbone and escalate the matter. I have hope that decent bosses will see the issue as a negation to good business, and I have seen senior management manoeuvre such behaviour to their advantage by going to their bosses to ask for their people to tone down or else.
It's all about power, and not every client is powerful, and not every account servicing is a slave. Look at your organisation, the annual revenue, the major source of funds that pays your salary, and decide for yourself if you have to be subjected to this abuse. For the middling people like ourselves, escalate whatever issues and let the bigger players pull their agenda. You don't have to suffer or bitch about it.
In any case, the best way to neutralise any toxic, is a reagent. An alkali neutralises an acid, bonds untangle into harmless components of water and gas. Similarly, individual components are innocent in itself, but under the right conditions react together to cause harm. Adding water, or a dilution, only brings down the concentration but does not its latent potency. Don't feed toxicity by avoidance or feigned ignorance. Tackle it, subvert it, even if you are the smallest fish in the pond, in your own way, in your own style.
To all the lies, deceit and hidden insecurities - I'd say, sunlight is the best disinfectant.