.htaccess redirect them or block them completely. I use a general rule that the tgp has to at least be English. I would love to not care about the bandwidth and just let everyone just add my url, but I honestly can't afford a place like gold.jp-sex.com (A japanese tgp) to pick my pages up. 1 day of them and I had 70,000 page views...on top of my normal 100k. Impressive to say the least, but completely worthless traffic to me and I just couldn't afford to be nice
So, basic rule, if the tgp is written in English don't htaccess block them.