What do curved lines effect have on clothes?

I am a bit confused about your question.

If you mean about like cut curved lines, then this is your answer:

If there is a curved cut line on clothes,

A.there may show your skin that you don't want people to see

This answer is about the design of the curved lines on clothes:

A. It may ruin the clothes that you bought or made.

B. It may just look weird.