Hard to put into a list, it was just the equivalent of a code smell. Some random examples:
- Fly out to the initial discussion, talk to their architect, some guy they imported from France in an otherwise entirely non-French company a long way from France (not bashing French folks here but just wondering where they dug this guy up). They've read about scalability and told him to come up with a design for that, which is distributed stateless everything (this was years before microservices and CRUD and whatnot). Except that they don't have the resources to build the stateless distributed everything so they're getting all the downsides of stateless distributed everything without getting the scalability that it's supposed to provide. You know its bad when one of the nontechnical sales guys that you're having a few drinks with after work can give you a breakdown if why it won't work.
- Parachute in for the first date, they've hired a bunch of kids straight out of college who are all hacking away at whatever they've been assigned to. So I'm walking around chatting to all of them, asking what they're doing and how long they think it'll take. Most of the time the answer is "oh, probably about two weeks". At the same time I'm running a mental Gantt chart for all the components and figure out that even if they meet their wildly, ludicrously unrealistic time estimates it's going to take them at least two years to get the product out the door. Some of their two-week timelines I estimate would take an absolute minimum of six months work, but probably a lot longer. Or a few days if they use the existing open-source tool that does the same thing, but they're going to do it better so they don't need to use any existing code.
- Site visit, the office manager screws up the travel arrangements, screws up the accom, the developers clock in at exactly 9am and down tools on the minute at 5pm so it's tumbleweeds in the office at 17:00:01, the mgt. is in a separate set of offices on the other side of the building and don't talk to the devs, over lunch the devs are talking about how much longer they'll stay before they start sending out resumes.
- The possibly-criminal one, I'll use an analogy to avoid identifying the actual job but lets say you've been brought in to develop an automated pen-testing toolkit. Not just a vulnerability scanner but something that then exploits the vulnerability. "You don't think that this could perhaps be misused by the people that commissioned it?". "Oh, we were so enthusiastic about the job that we never even thought about that".
You may have noticed a common theme here, talking to the techies and/or taking them out for lunch/drinks. So if there's one takeaway, it's do that. That's how you'll find out whether it's an organisation you want to get involved with or not.