As a former hotelier, and one who worked for a national midprice chain in quality assurance in the mid 80's, let me share a little bit with you.
Many hotel properties, acutally most, are franchises. Most franchisees own properties affiliated with several chains. Some chains have stringent standards while others are suspect. Some chains enforce their standards while most look the other way, for the most part.
Many franchisees will actually run all of their properties to the lesser standards and tell the chain that if they don't like it, they'll change their affiliation. It's not that tough to change. We have all seen the revolving door game played by properties. A lot of times it is geographical as well. What is acceptable in Paducah, Kentucky would probably never fly (no pun intended) in Seattle.
The less you pay, the more apt you are to find such inconsistencies, although there are exceptions. I have found Hamptons to be very good and consistent. I have never had a bad stay with Hilton, but have been in Holiday Inns and Sheratons over the years that were no better than a flophouse in France!
Even had a horror story at Westin in Kansas City a few years ago and since college days would have NEVER expected that. I would go so far as to say that "You get what you pay for" is not applicable anymore with lodgings, because I have had some great budget stays in places like Paducah, Marion, Council Bluffs, Cherokee, Clinton, Athens, La Mirada, etc.