I do alot of buying on ebay so heres an example:
1) Seller has 0 feedback - it could be he's new user but there's a 90% chance hes a scammer
2) Price is low - an sx740 goes for $450-$650, 220 is way too low. red flag.
3) Pictures - all stock photos. None of them taken by the seller is also a reason its almost for sure a scam.

With eBay though, if I see a good deal, I grab it. I know eBay will always have my back.
I randomly sell things on eBay. 99% of the time, I'll use stock photos. (Unless it's a used item, and I want to show the usage)... With a case like this, it's a red flag. Ordinarily, not.