spam, not scam.
peeps advertising stuff on here, particularly if it's not in the for sale section get generically labelled with spam, as in unwanted or unsolicited advertising, like the emails you get.
he is in no way referring to your trustworthyness, merely the fact that you a hawking your goods on this forum, and even then I pray suggest it might be slightly tongue in cheek as it does hold relevance to the original thread.
I should also like to point out that I am in no way condoning nor condeming your actions and/or trustworthyness, just explaining a point of fact.