I believe the reason why BBC does not have adverts and the other channels do is because the BBC is funded by the TV license. If everyone got a chunk, the BBC would play adds too, which is why BBC radio play ads (because you dont pay for a license for that). Also, the license fee would have gone up by about 1/5th when Ch5 came into operation, but it didn't.
But on the subject of big brother, I personally havent ever watched any of them closely, but I'm loving this years big brother. I actually stop what I'm doing to watch it. I think if people are stupid enough to go onto a game show and forget the fact they are on live TV 24/7 then they deserve everything they get. Violence and mass arguments are about the only thing entertaining about it!
I look at the calibre of people who go on big brother and I sometimes have to remind myself they come from the same country as me. It's almost like the requirement to get on there is to have the IQ of a lettuce. An example of how odd it is, is that the most rational, sensible and mature person on there is a bald headed homosexual psychology hobbiest called Dan.
Don't forget either that half of them will make a good buck or two from humiliating themselves. Look at that Jade bird from which ever BB it was. At the time, widely regarded as the most stupid and unattractive blonde in the universe, now gets on TV, in magazines, and people have forgotten how much of retard she was.
There's no long term damage, except to quality of television.