You can easily turn avatars off on FTP from options. It's also fairly simple to customise the backrounds/cards on most sites. You can just download a skin you like and replace the graphic file in the directory where you have installed the poker site.
For an example, my partypoker looks like this:
By doing a google I found this site which appears to offer skins for many poker sites.
Also there are many affiliates saying you can e-mail them even if you already have an account at FTP and they will help you set up RB.