I can't claim to be an expert in the roofing business, but I do know the flooring business. Most companies do subcontract their carpet installation. The quality of the installer is usually directly related to both the pay that can be attained from a particular store, the amount of work they generate to keep the installer busy and the individual expertise of the sales people at that store. From what I understand, the pay at these types of stores is not bad overall. The amount of work generated can be more of a problem, as these types of stores typically cater to a cash and carry, do it yourself crowd. If an installer isn't busy every day, the pay rate doesn't really matter. The biggest problem quality installers have with these types of stores, however, is the quality level of the sales people. Poor sales people will create all kinds of headaches for the installer, and will tend to generate false expectations and the installer ends up on the hook to live up to them.