I didn't know until this thread that this form existed outside SE England. So "smart ass" -a cunning person, negative comment. Said when someting is rather good instead of just "good" or "OK". Please don't make us guess. This usage is unknown in AE in my generation!
Cecilia. Age: 32.
I saw its written "sweet as" but pronounced "sweet ass".
Royal. Age: 25.
sweet ass or sweet as?
So, I'm sorry, w h at do you think could be the reason for as to be there? Please don't make us guess. Toadie Senior Member Maryland. It is, in essence, a castrated simile; a concept that is particularly useful for those of limited vocabulary.