Ask questions during interview.
Ask about trainings - it's usually a good sign when company offers training budget. Ask about specifics - sometimes it's a shared pluralsight account, and nothing else, which means that that had an idea and half assed it into existence.
Ask tech recruiter about overtime, a good sign is when they have no idea or say that it must be budgeted and scheduled - it means that it does not happen often.
Ask if it is possible to select and change projects, and how often it happens - if often, it may be bad low level management, or people learning new things and jumping between projects.
Also make sure to ask about rules for promotions and pay rises. Good company wił have a clear set of rules in place.
All of the above apply to mid to large companies.
For small company, i'm sure it will be different.