'Bad skills' is a term to be used in scorn when a peer has shown a clear lack of skill during an important task. 'Bad skills' would usually be reserved for an occasion on which the accuser feels that they would have performed significantly better were they in the position of the accused.
There is absolutely no call for the phrase 'bad skills' to be used erroneously in a situation when the person in question was simply 'f-unlucky'. In these cases they are to be excused and consolation is in order.
Here are some situations where 'bad skills' could be blamed for someone's failings:
1. During the final frame of a match of wcs, one player is clearly in a position to win. He has had several red-black combinations already, and with the reds pretty well spread out, the game would appear to be in the bag. The player relaxes rather, and gets a little too over-confident. He over-hits his shot on the black, sending the cueball up the table, burying it behind the green, snookering himself: "Look, mate, that's bad skills."
2. On entering a crowded late-night bar of sorts, the choice of drinks is surveyed. A foreign lager by the name of 'Leffe' is spotted, and one person decides to give it a try. Boldly, he says "a pint of Leffe, please." He fails, however, to check the price before doing so, and is shocked to hear the reply, "that will be £4.50, please:" "Bad skills, mate."