Nifft
Penguin Herder
Only in table loaded with other munchkins. If you have that utopia then all is well. In a regular group, someone who is only out to have their fun at the expense of others is a fun vampire and needs to be staked from the table.
If you allow the guy who is good at mechanics to do your character's mechanics, then you get many the benefits of munchkindom without needing to be one yourself.
(That's how many people handle real-life mechanical issues, too: they pay a mechanic to fix their car, rather than try to do it themselves.)
If you insist on fixing your own car, and you also insist that you must be allowed in the race with a car built by an expert mechanic, and you care about the relative performance of your vehicles -- then yeah, you're not going to have fun. But that situation is due mostly to your own issues, rather than the fact that mechanics exist.