I once was going to work for a friend's startup but we didn't see eye to eye on everything and decided to not work together. As a joke I said I would go work for the competition which ended with a 2 hour interview in a town an hour away with the competition. They offered me a job doing backend work however I wanted to develop frontend so I didn't take that job either. What interested me is that in a 2 hour interview I learned everything about my friend's competition's business model and future plans. I've never done it since but if someone wanted to know what another company is doing apply and ask a bunch of questions during the interview. Asking too many question during an interview isn't a thing.