TweeterAdder forces you to add all the VIP (people who buy slows) and at least 20 people to get your own account listed. They may randomly (you have no control) use your account to advertise your services.
Heck, let’s just look at their Terms of Service:
1. You agree to submit your twitter account credentials.
2. You agree to allow us to store your account information in our database.
3. You agree your account will be used to automatically tweet an update on your account for promotional purposes every 4 hours with the exception of VIP members.
4. You agree upon loging in you allow us tweet an update on your twitter for promotion.
5. You agree when buying vip there are no refunds or returns what so ever.
6. You agree to allow us up to 6 hours to put your twitter user name on the vip section.
7. You agree if you spam our site you will be banned from our service forever with out hesitation.
If all of this does not scare you, then go for it. Give up your account. Let it get spammed and follow those you don’t care about.