Aguila wrote:
I was wondering what the best way was to genuinly tell somebody their artwork is amazing even if they think it looks like crap.
Tell them
why it's amazing.
If you say something like, "I love your use of colour. The contrast between that foreground figure and the trees in the background, the way he stands out and seems more real than the rest of the composition, that has great impact," then it demonstrates to the artist that you really are looking at his art and thinking about the peice. If you prove that you've really looked at the thing, your opinion about it will mean more.
If you just say it's amazing, with no explaination, it may frustrate the artist for two reasons. One is that most people will always say, "It's good," if shown somebody elses' creation, regardless of what they really think. The artist doesn't know if you're just being polite, or if you just want him to like you, or if you really like the art. The second reason is that if you don't say anything specific regarding what it is that's good about the peice, the artist doesn't have any useful feedback to help him decide how to improve.
Or, as donkey says, they may just be playing the 'fishing for compliments' game. But in that case, still, telling them a bunch of reasons why it's great is giving them just what they're fishing for, a bunch of compliments.