CC doesn't make the game weird in general. People state that like cc is guaranteed to mess up your game. It's silly really. I've been downloading and using cc since the Sims 1 and the only negative I can see is the longer loading times. Really though, it's worth it. All the extra content for free.
If you download content from reputable sites you can expect a certain standard of quality.
I think some people try cc in their game, notice something weird and instantly blame that when in actuality it's just the game is full of bugs.