re:
 

Yep, if they are cheap.

However, people are right in saying that your shape can change even if you fit the size.

I wore the same brand/style of jeans for years and they went on sale for 14.00. I bought sizes down to 16. The 18's (and prob the 16 im guessing) look just awful. They fit, but the shape is all wrong now.

I guess the moral of the story is probably not a good idea - I try everything on now.

Usually I buy something that fits but just a tad tight in some areas. Usually after the first couple times of wearing it it fits really well.