In the recent market it's very tempting to take any interview a search firm calls you for. I know it's a two-way street here.  The recruiter needs to be diligent and ask all the right questions and provide all the right information and there are often unknowns on both sides--but if there is something gnawing at you early on, or even after the process has begun, don't wait until the offer is being negotiated to bring it up. During the interview and hiring process surprises are most unwelcome. 

I've been extremely grateful over the last few weeks to a couple of marketing pros for not putting me in a situation that could have damaged a relationship with my client.  They were thoughtful and upfront about why they might NOT be a fit for the position, rather than hope they could change the job requirements or the logistics.  In one case, it just wasn't a fit and we moved on.  In the other we were able to address the potential concern and work through it.  To be sure, neither one jeopardized future opportunities with me--if anything they improved them.