Yes, because I can take song X, recorded by artist Y and change something and sell it as mine.
...common sense to stephen, can you read me?
If you want to be safe, you don't use someone else's models, period. If you want to nitpick, there probably is some point where the original content becomes so insignificant that it wouldn't hold in court (but that point is certainly much, much farther than "something"), but that would do nothing to stop someone from suing you.
Wouldn't it be just simpler to do the right thing, and build the models from scratch, rather than try to come up with ways to justify stealing?
