The big “oh crap” moment is when a more experienced/senior employer quits, and you realize their work was much worse than anyone thought.

Another issue is when the core product itself is faulty in a way the customer will notice. That sounds obvious … but it’s not.

Also, hitting a growth spurt with no full time product managers. That’s not good.

Unethical practices. For example, if you’re asked to generate “rosey” sales reports for the board. In fact, anything where you’re working against the board screams: “Run!”

Being very liberal with stock options. Nothing says “failing company” like a comp package that’s mostly options.

Also, pay attention to the quarterly cycles. If the company is going to collapse, they’re probably going to collapse at a quarter mark.