If the game they are playing is golf, then 'scratch' refers to his handicap. People with different skill levels play golf. In order to even things up, golf has a handicap system. Basically a player's handicap is an indication of how many strokes over par he is expected to need to complete a round. The weaker your golf game, the higher your handicap. Amateurs can deduct strokes from their scorecard according to their handicap; the higher your handicap the more strikes you can deduct. The very best amateur golfers (and all of the professionals of course) have a zero handicap. That is referred to as a scratch handicap and you'll often hear the players with zero handicaps referred to as 'scratch golfers'. It just means they're very good at the game and have a zero handicap.

Hi Mehrdad, It's a strange sentence, but usually when someone is a 'scratch' or 'scratched' it means they can't do what they are scheduled to do - it usually relates to sport. This comes from horse racing I think, where there is a list of horses that are scheduled to race and when one can no longer race because they are injured for example, then a line (a scratch) is put through their name on the schedule. In this case, Roy is a scratch (can't play the game/sport) and he wouldn't want to spend time with someone who doesn't care about playing like the author. Hope that helps.

scratch or crap?

This is a strange sentence. It needs more context I think. The only thing I can think of is that it is an abbreviation of the term "Up to scratch", meaning he's as good as is expected. You might say "I practised hard and now my game is up to scratch". It possibly makes sense here, but I'm not certain.