My uncle has some dull-sounding industrial machinery sales job and always goes on holiday to Canada. There's a definite pattern.
There are very few places I'd actually refuse to go if someone said "look, here's a free ticket to X". I'd probably hand it back to them if it was to somewhere completely lawless and violent like Somalia, or a country that's desperately poor. But there are places I'd go, but not be bothered enough about going to ever make it there, if you see what I mean. I'd probably avoid the well-worn South East Asia backpacking haunts, for example. Nor do the British beaches of southern Spain feature highly in my fantasy travel plans. In fact, I'd go as far as to say I'd steer clear of anywhere that's had a "holiday reps uncovered"-type TV programme made about it. (That makes me sound such a snob, but I'm just not a big drinker and I prefer my beaches big, empty and on Scottish islands!) Aside from that, there isn't really anywhere, except places fairly local to me that I just think "oh no, not that place again", like Blackpool or Birmingham.