In your case, you are not shilling roobet because this site has a good reputation IMO.
So by that logic, if Roobet did
not have a good reputation, you
would call him a shill?
I thought so, can't really find the exact definition of shilling since it's not in the dictionary, correct me if I'm wrong, but according to the meaning you posted.
According to Google, "Shill" means: "an accomplice of a hawker, gambler, or swindler who acts as an enthusiastic customer to entice or encourage others"
IMO, you would not shill a scam project if you are not getting anything in return, and the fact that you know you are promoting a scam project, that means you are an accomplice and you are a scammer as well. In terms of determining its reputation, I think that's one of the hardest thing to do especially if the basis is our opinion here, unless a certain project is deemed declared illegal by the regulators.