I haven't slept on an air mattress since I was a Boy Scout. They're heavy, and even the old milsurp ones were a pain to fill. I have slept in a lot of places like you're describing, and I can deal with smells and lumps. Bed bugs are kind of a rarity here, but my grandpa always urged me to stay in "dollar hotels" (he was a salesman from about 1950-1990) and that I need to sacrifice comfort in exchange for a cheap place to crash.

In all the rough places I've slept, I've never worried about bugs. I've seen spiders in the tub or mosquitoes, but nothing too serious.

Those small town hotels tend to be in good shape, because (at least before oil prices went way down) they were often fully booked by people who were staying for many weeks at a time. You used to be able to book a suite at a roadside motel for 50 bucks which had a stove, a fridge and a warm bed. Less money if you stay a week and less money if you stay a month.