gotlurk for your own private use but not for BBT. Except you can find the original filenames. Besides, it's a no go for BBT for it's being scanlated.
newy, I think your misinterpreting something

...
"Official manga is allowed but not doujin" <= that is what you must have thought of? However that's got nothing to do with the issue at hand.
Scanlation = translated (often cleaned as well) japanese manga (raw from magazine/tankoubon)
Scan = Scanned R1 published manga (publishers:TokyoPop/Viz etc)
If only manga published in R1 was allowed, the list would be very short here on BakaBT...
Also, saying #lurk isn't allowed would be like saying TT isn't allowed for anime, because in a similar way they're a hub for most manga releases (or at least they used to be)... (have you ever seen single bots with close to 20.000 packs of manga? Try a visit to #lurk@irchighway...)