The criteria and standards of the CBB line ups are completely different to those of SCD though, you can't compare the two. CBB is mostly based around drama so naturally other reality TV stars cause the most drama, hence why so many are cast on CBB, Also, it's much trashier and would be considered much more low brow than SCD so there's not going to be a queue of A List celebrities wanting to sign up. It's also edited and set up in a way to bring out the worst in people, and very often the celebrities are not depicted in the way they'd want to be, so the only real reason for people doing it is money or to become more famous.
Strictly, on the other hand is completely different, it actually involves learning a skill and is all round a much more positive show than CBB, the majority of people who go on it see it as a positive experience. Furthermore, it has a much better reputation as a show than CBB and is one of the highest rated shows on British TV right now. This explains why generally they get bigger names, people don't see it as selling out if you go on Strictly as it has such a good reputation and there are so many other reasons to do it other than money or increasing fame. That is why we really should be getting a better line up for this Strictly series than what we've got so far, I'm really surprised that this is the best they could do and that's why I'm finding it so disappointing so far.
The calibre of celebs they get for SCD and CBB are world's apart so to use the fact that the current Strictly line up is better than the rumoured CBB line up is a moot point. They day that the CBB line up is better than the Strictly lineup will be a VERY low point for Strictly, and would mean that the show would be in need of an imminent axing.