Checking bank references is not out of the ordinary. A builder or contractor with poor finances may not be able to complete your project. The local BBB can tell you if there's anything derogatory about the company in their files. If the company has recently come from another locale, call the BBB in that area. Be cautious here.
Contracting is complex and a large company is likely to have more complaints than a small one.
The question that becomes important is not so much whether there have been complaints, but how they have been settled. If they have no local phone number other than the motel down the street you can figure that warranty work is going to be awfully tough to finish. Your best bet is to speak directly to others who have recently used the company. Run, don't walk, away from companies that demand all cash up front or even a hefty deposit. Legitimate companies won't demand to be paid in full prior to rendering a service.