We're skint, or bad payers.
I received a telephone call out the blue from a company supposedly based in Buckinghamshire, at least that's what their website says. Caller: "Hi, I got your details from your website, I understand you provide computers. Do you do parts as well?" Me: "Yes we do." Caller: "OK, I'll send you a list of our requirements, can you quote me please?" Me: "Certainly." An email arrived asking for some branded laptops, base units and CPU's which I duly quoted. A little while later I received an email back. Caller-Email : "Thanks for the quote, I've spoken to our accounts department and your prices are acceptable. They have asked if this order could be on a 30 day credit account?" Me-Email: "Sadly we will require full payment prior to order. This is because we have no trading history with each other. I'm confident once we have processed a few transactions with each other an 'invoice' relationshi