Man I know that pride doesn't take punches but being totally regarded as a tuneup and then having the media and your opponent talk about the fight after yours just has to be a terrible feeling on a personal level.
I can't even wrap my head around this question. There's always the underdog in many fights and most fighters would love to be perceived as the underdog. It lessens the pressure and lowers expectations. I don't know what is wrong with that.
I bet if you make a list of tune up fights that turned into upsets, in the entire history of boxing, it probably happens often enough that you can see it as something worth your while as the tune up.
I think younger fighters would be thrilled at the opportunity to step up big time. Younger fighters, especially undefeated ones are full of confidence that they can be the spoiler and move up the ranks.
I think older fighters who are considered tune ups already know their role. Not that they don't believe they could win, but they know they're being set up as a stepping stone for a bigger star fighter.
Most fighters would probably be thrilled to get the payday and chance to upset the kind of fighter who actually fights tune ups.
I'd probably be one of those.