As much as we like to think it, I'm sure most WGs don't truly enjoy most sessions in their work regardless of race.
Some of the bros mention that some WGs will screen them out cos they don't like to do foreigners but it's just a case of finding ones that are ok. There are plenty out there.
i would like to know how does this sex service works.
Read some more of the site including the stickies at the top of this section. This link goes to a newbie guide thread:
http://forum.sex141.com/eforum/viewthread.php?tid=2104
If you have any other more specific questions, post them.