Yes, it definitely not a recent bankruptcy problem. US Air either has to clean the cabins frequently and properly or refurbish them on a regular basis. I have actually noticed that the Airbus Shuttle cabins are starting to look a bit grimey. They have been in service for ~3 years.

It really creates a bad image and I am amazed that they don't anything about it. UA's old Shuttles are very clean but probably as old as US's Boeings.