[Dr. Meatgrinder]

Incompetent: Hardware would bone a player WAY too hard in most cases, that's why I wouldn't allow that one. As to others, as long as it isn't Magic or Resonance linked, I could care less if someone takes it, despite the fact that it doesn't close off learning the skills entirely, it just doubles the cost to learn them.

Actually, Incompetent does close off the skill entirely.  "Characters may not possess that skill, nor may they default on it" (p. 95, SR4A).  You may be thinking of the Uneducated quality.

[Dr. Meatgrinder]

My Christian Theurge character has Incompetent (Binding):  "One does not bind an angel of the Lord."

[Xzylvador]

Knew a Face character in a PbP I was in with Incompetent (Intimidate): The guy was simply too kind for it. And if he would have tried to intimidate anyone it wouldn't have worked because he walked, talked and acted like someone who wouldn't harm a fly, no one'd believe he could actually want to cause you harm.
Seemed very fitting.

Had the same thing Fringe did on a magician character, too. All kinds of good RP reason for magicians to be Incompetent at Binding, Summoning or Banishing. If they choose to roleplay that way, why not give them a small BP advantage for willingly not using something that might otherwise give them an advantage in game?

[emsquared]

Incompetent is the worst.  There is no better way for a player to advertise that they don't want to roleplay than to take Incompetent in anything.

Either the player picks some skill that they will never have any reason to learn or use (because they're greedy and don't want their disadvantages to be interesting or disadvantageous,) or they pick a skill that they might have reason to learn or use, but which would be completely insane for a person to be unable to learn, do or understand (because they have no concept of their character as a person who exists in a world.)

There are not enough rolleyes smileys in the entire internet for this shit quality, so I'll have to make do with this.

Yeah, this may be just a tad bit hyperbolic.

Especially if it's combined with other similar Neg Qualities, incompetency isn't 100% cheese, 100% of the time. They can be used to fill out an RP-crutch. Take Asthma with athletic incompetencies, Gremlins along with technical incompetencies, pacifist and/or combat paralysis with some combat incompetencies (or xzylvador's intimidate example), uncouth or uneducated could pair up well with some incompetencies. List goes on.