I never made it beyond a college lab, but one of the things that worried me most (and that, more generally, continues to worry me in life) was a screw-up or deliberate maliciousness on the part of others in the workspace.
I recall one time happening to see two other students applying solutions to the faucets handles of one of the lab desk sinks after a lab, because they thought it would be a funny prank upon whoever next used that sink.
Other times, stuff gets spilled by people who don't know better, don't understand the resulting risk, and/or just don't care enough to "do the right thing". And so inadequate cleanup leaves traces for others to stumble through, likely with know knowledge of the problem.
In my subsequent life, outside of a lab, I've repeatedly encountered significant health risks created by as well as ignored and/or abandoned by people who "don't know" or "don't care".
In broader life, buildings are full of lead, asbestos, and everything else, and putative penalties aside, it's basically "buyer beware" as far as inheriting someone else's problem (inheriting to your own personal liability and financial risk, not to mention possible health risks).
As much as "stuff I won't work with", I've developed an attitude of "people I won't work with".