Nothing really boils my blood more. As a former fitter, I was always very open about costs and trying to make something work (performance wise) and get their budget up front and told them there was no pressure. I didn't force anything down their throat, but always was able to significantly improve on distance AND accuracy.
What bothered me was the the guys that would gain 30 yards with distance (and no it's not just the loft), as they were apexing at like 45-50 feet, with 30º land angles, and I'd be picking them up tons of distance, and their accuracy was like Bob Lee Swagger avenging Donnie's death. At the end, they'd go with something we didn't even test, so they could get stock, and "support their club" even when their Pro doesn't own the shop. We didn't upcharge anything (straight retail), and we'd even offer to price match whatever discount they got through their club too.
I didn't tell people how I was paid, but I didnt make a dime unless they bought clubs from me. None of that fitting fee goes to the fitter, it's straight overhead costs to pay for trackman and keep the lights on.
I guess to summarize, I don't mind if people go elsewhere, it's more-so the lying to me about your budget and telling me you'll be buying (When I have hard data to show you we blew it out of the water), and then you get something totally opposite that doesn't work, and I just donated 4 hours of my time for 0 cause and nothing to show for it.
It's like paying to go to the doctor, they give you the cure for a very rare disease...and then you go on a forum and say hey, do you think Ibuprofen will work? I think I'll just give that a shot.
/Rant.