Ask HN: Former founders, how do you evaluate culture while job searching?

Background-- I'm asking as an former startup founder who was very thoughtful of building the right culture. Now I'm interviewing for PM jobs at companies of various stages, and I'm wondering how I should judge their culture. Not to apply cultural relativism to tech startups, but surely I shouldn't (exclusively) judge companies' culture based on how I wanted to build my own. Something different than what I planned could be working well for them, and also evaluating as a founder should be different than an employee, no?

Other related discussion points-- -- How is evaluating a company overall as an employee different than evaluating your own startup as a founder? -- Anyone else finding the interview process odd after a while at one's own startup? (There should be a support group.) -- What are some of the most serious red-flags culture-wise in a prospective company? For example, having unclear compensation structure is often seen as a red flag by veterans and some VCs, and startup founders are told to avoid it; how serious is this at a series C company?

Request-- In your comments, please at least mention the stage of the company you're referring to, since I suspect this differs a lot by stage (any other details are great).

Note on definition of culture-- Culture is a nebulous term and can mean a lot of things (timely NYT article on HN today). When I say culture, I mean the hard, tangible aspects of a company that shows what they care about: for example, being open with emails like Stripe shows that they value transparency; not having titles at work shows that they think themselves a meritocracy; etc.