Each person has a different definition of spam. Each manager is different as well. You've hired spammers, I've hired spammers, everyone has had a few. Just report the posts you feel are spam and if they see enough reports, i'm sure the hammer will drop on some participants. If enough get banned a warning might be sent to the company before any bans happen to them.

I really don't think trying to get a company banned is a good thing though. Last resort maybe, but def not the 1st step IMO.