Only the Canadiens Fan to Fan Verified marketplace can guarantee 100% legitimate tickets, because the seats sold through Canadiens Fan to Fan Verified marketplace were first sold using the Canadiens ticketing systems. If you buy a ticket that is resold through a source other than Canadiens Fan to Fan Verified marketplace, you have no way of knowing whether the ticket you purchased is counterfeit or has been invalidated. However, with the official team resale platform, once you buy a ticket, we cancel the original barcode and assign you a new one, so you have the security of knowing with certainty that you have a verified ticket. Buyers simply select the seat(s) they want based on price and location, without having to bid against other buyers, without having to coordinate delivery from anonymous sellers, and without the gamble that the seats are illegitimate.
Don't be fooled by other website guarantees: there is a lot of fine print and exceptions in those guarantees. They do not have a way to fully validate the authenticity of the ticket.