Not completely true, Stormy. Only if a CD is parental advisory is it edited. However, if it has coarse language-- just not enough to be PA, it is not edited. For example: I bought Disturbed's Indistructible there, un-edited.
If an album has a parental advisory sticker on it obviously it has swearing in the album, however most PA albums now a days have edited versions released as well, for example Linkin Parks "Minutes to Midnight" album. However bands like Nickelback use some swear words and their albums aren't given a parental advisory sticker. So my point being is yes amazon has edited albums on the site, but also it sells unedited albums here as well. And in some cases, Nickelback for examples sake, don't have a parental advisory sticker on it, but it does contain swearing on the actual album.
So you're best bet is to know what the albums contain and proceed to buy them with caution.