How can I learn about workplace environment possibilities early in an interview process?

I've experienced a problem several times now in which I do well through interviews, I ask many questions about the working environment, and when it comes time to negotiate an actual job offer, I learn that there is no flexibility in workplace attributes -- which are often dealbreakers for me.

I've tried asking HR reps, recruiters, hiring managers, and peers, at all stages of the interview process, and I find that their answers to my questions are generally inconsistent with each other and usually unrelated to the realities that surface at the negotiation stage. This has happened in a similar manner in 6 different companies over the past year, and some precursors have happened in at least another 10-15 companies where I did not go as far in the process.

By way of example, I once had a series of interviews going from an initial HR phone screen all the way to a "what can we do to get you to join our team" interview with a senior manager. In that sequence of events, different people described the workspace options ranging from "We are very flexible and we'll accomodate what you need" all the way to "It sounds like you're not a team player if you don't want to work in our current workspace." The same sort of thing happened in the other 5 places too, in various incarnations, and the companies involved ranged from 10-person start-ups to 10,000+ corporations, with no distinction between them.

The only consistent thing I've found is that everyone in a company (even two different managers of the same team who work together all the time) has a different opinion about what's possible regarding workspace customization, and at the final stage it always reduces to effectively "no customization is possible at all and it reflects badly on you that you even ask about it."

If asking very directly leads to information with such little correlation to reality, what process can I use to obtain more accurate information about workspace customization options?