I think there are two types of qualities. Quality as in looks and quality as in feel. Nowadays I usually deal with QQ girls. Since there is no money exchange explicitly (there is cost of other expenses such as dinner), they have the rights not to ML. Sometimes it took me more than an hour to half coax and half 強姦 to get any result. And during this 交流互動之間, we developed a closeness which is more enjoyable especially when ML. Seems like we had to work for it (in the process we laugh and bargain and I beg etc.) and then reach climax when we finally ML. The chance of quality in looks is definitely higher when girls from KTV or SN are involved. But I think the quality in feel is also desirable with QQ girl when she gives you the girlfriend feeling. I am not saying there is no true feeling with KTV and SN girls, but in the back of your mind it is hard not to doubt her intention and her motive. Of course if one can have both qualities in one girl then it would be the ultimate. Poor me, I haven't met one yet.