The domain name is very recent (less than 6 months) It is usually a bad sign. Most scam web sites use new domain names.
The domain has no mail server. This is a bad sign.
The domain uses a free_email. avoid online shops that use free emails (e.g. gmail, hotmail,outlook)
This website is not popular
This domain is suspected to be a source of SPAM
This domain is using opencart platform