> How can one be a "shill" when not selling anything?

That a very narrow interpretation of the meaning of "shill." Here is a more comprehensive definition

> an accomplice of a hawker, gambler, or swindler who acts as an enthusiastic customer to entice or encourage others
> a person who pretends to give an impartial endorsement of something in which they themselves have an interest

https://en.oxforddictionaries.com/definition/us/shill

Also, when you get right down to it, just about everyone is selling something. 

PLB

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html