You may think bad of me for saying this, but I've always thought that "Great model, but I build for fun" or "Great model, but I build just for me", are just excuses for, "I don't know how, and I'm too lazy to learn anything beyond "paint and assemble".
Don't get me wrong, I know that there are some with physical, mental or financial handicaps, that can limit ones ability. I'm talking about the person who gets tweaked when you offer constructive criticism on their basic building skills, and they throw that "I build for me, I don't care what you think" at you. Odds are they won't be in the hobby long anyway.