It's up to the gig to make things appealing in their workspace well before it's time for me to get them interested in me. I interview them just as hard as they're interviewing me. A shitty interviewer usually means a shitty place to work. And if I'm tricked into thinking it's a good gig, but isn't, I leave it asap. Easy. I owe them nothing if they can't deliver what they promised in the wooing stage.
I'm totally happy to share my income with a headhunter who brings me good gigs. If I see loopholes that clearly work against me, I'm gonna walk away. It's not like I should blindly accept anything just for the sake of a headhunter's commissions. Especially since there are so many good gigs out there.
Just like at the casino, one should only walk away from losing opportunities.