"So, yeah, beware: if it doesn't take Paypal it's clearly a crook."

Interesting theory but I’m not sure how far it works out. On a short random sample of our family (non Amazon...) online shopping this year, from plumbing supplies to gardening, most do take Paypal. A couple of exceptions I noted were Nisbets (catering supplies) and Radmore and Tucker (gardening/forestry equipment). Both of these do sell to many casual customers and are not what I’d consider “fly by night” firms.