One who is of questionable cleanliness. Alternatively may be used to indicate that someone is a bit crazy. May be abbreviated to "scaff".
The origin of the word is unknown, as it was overheard on a Scottish train by a group of neds
, as they parleyed insults with each.
After much debate, it was decided that the word probably relates to a bin bag, with "scaff" being a slang term for rubbish/dirt, and a "bag" being a common receptical for objects.
Not to be confused with "Scaftag", an advertisement medium associated with scaffolding