Unselfish in regards to..if i am willing to solely suck your dick..and thats all.. there is something sexy about that in most men's eyes.. A girl that would eagerly suck a guys cock and expect nothing in return is sexy..
as far as paying.. well.. some are only unselfish when they have some benji's in their palm lol
or alteast more eager.. .. but still.. pay or not.. still something sexy about a girl that is eager to please with her mouth and doesn't leave you feeling as if she wanted something in return sexually etc..
While i'm not a huge fan of DATY.. what makes it even more sexy is if/when a guy did that and doesn't expect anything in return..just wants to lick me to get me off and he got off knowing i was totally pleased..
thats kinda how sucking a guys cock works for me.. totally unselfish.. and if the guys mind is right about it.. it makes it hot for him to just allow that