There is no reason you should be eating at the Denny's in Killeen. There are two other 24-hour breakfast/diner restaurants practically within walking distance of this nasty establishment. The IHOP has crappy service, and Kettle has a run-down looking inside and allows smoking, but seriously, you are way better off with either of those.
I've been in the Killeen Denny's three times. It smells really bad in there. It smells strongly of urine and cleaning fluids which I guess they used to clean up the urine. All three times it smelled like this wherever we sat.
The service was sub-par, at two visits...