Just to make 100% sure that everyone understands how skimming works, I'll repeat my example here..
Load up
www.picminer.com/tgp.html
Pick a thumb and click on that same thumb 5 times. Chances are you will see the gallery 3-4 times, but the other times you will be 'jerked' to a trade.
Trades are other TGPs. Traffic is never skimmed to another sponsor. You will only get the gallery, or another TGP.
This method of trading is very effective at growing sites. It is relatively easy to grow a skimming site to 50k without needing much (or any) feeder traffic... you just need to find the right trades. To grow a skimfree site to the same size would take a lot of time and expensive feeder traffic.
Remember, since skimming is now the norm for TGPs, surfers are accustomed to seeing other trades occasionally. Even new surfers will quickly work it out.