I will sometimes tag @SexyLadyShow because I've gotten some good paying customers from his account. But it's not something I do every time, and his is really the only one I bother with. Way too many of them seem to want at least attention (if not free Skype shows and the like). Some of them do get paid, through advertising or affiliating with specific sites. I assume this is just the bigger accounts though?
I think if you just want more followers (which can be beneficial, as having lots of followers tends to lead to more followers), it could be good to tag them, but I don't think it's super useful most of the time and I'd only use the most popular ones, personally. Tons of camgirls have way more followers than the promoters, yet they still tag them in every tweet. Like Steph, I find it off-putting when girls tag a billion promoters in their tweets.
For me, I would rather focus on getting guys from my MFC room or my C4S store to follow me, than just a bunch of randoms who like free boob pictures.
I also think you are more likely to get interactive or interested followers from interacting with other camgirls - again, lots of them have more followers than the promoters, and their followers are more likely to already be interested in camgirls as it is. I don't think tweeting popular models saying "hey can you RT this for me" is good form, but I think it's fun to tweet with other girls or retweet their pictures. If I'm not camming that day, I might RT or suggest a girl that I think my guys would like in hopes that they'll go visit her. That kind of thing.
(Also WOW could I have said "followers" more times in one post? :lol: )