We should also point out that Peaches was a worldwide #1, despite using the "s" word and the "b" word. So I guess it wasn't much of a problem. It peaked at #4 in the US Adult Top 40, and it was mostly Top 10 in some eastern block countries. It was #1 in the Netherlands, Denmark, and Canada.
In the other thread, we discussed how these edits are done. It's rare that a radio station itself does the edit. Typically the record label does the edit. They might request the artist or producer to do an alternate version without an offending word. The word "ass" comes up a lot in songs, and record labels will often find a way to replace it. It may not be one of the FCC's deadly words, but some find it offensive, depending on context.
When the edits are done by the label, they can be less obvious because they have access to the multi-track. Radio stations prefer not to air a song with a bunch of beeps in it. They'd rather not play the song at all. From what I can see, the label did an edit on the Bieber song that minimized the impact of the "s" and "b" words. You know what he's saying, but he doesn't actually say it. Some grandmas might be a bit shocked that he would say such things, but he's been doing crazy things for a long time.
Here is an example of a clean edit of the song:
This version is pretty innocuous and could probably air on an AC station (although the song didn't chart AC).
Someone has done an article on the general subject of radio edits for Wikipedia:
en.wikipedia.org