I open the trade accounts for my company.
They need to complete an account application form, this will ask for 2 trade refs & bank details among a few other basic questions.
They are checked out on line, (we subscribe to a service). If they have a good rating the account will be opened. Sole traders are the difficult ones.
If the rating is not very good or they are a new company, we will apply for the trade references.
We refuse very few, but all are checked.
If a company has previous trading history with us ie credit card, we will usually open the account, although maybe with a low credit.
If its a multi million pound plc we will open the account prior to receiving an account apploication, but we still request one.