Your right, but so is Danny, they keep the glass and deco's clean, easy to wipe the tank down with a pleco.
Rule of thumb, the bigger the Pleco the bigger the turd!
Chineese alge eaters are a lot better at cleaning the glass...and they poop less......I'll take some photos of the glass on my 265 when I do a water change...it looks like the belly of a snake from the mouth marks of my c-algee eater. I have an 2 large plecos in the tank an I had never seen mouth marks up till I added the c-algee eater.