If smoking or pets matters that much to you then ask before driving to see the trailer. Get as specific as you feel you need to.
Reminds me of the princess and the pea. People have different levels of sensitivity to different things. I can't stand strong perfume or scented candles. Smell of cigars does not bother me.
We don't smoke in our 37 year old trailer but I found a cigarette burn from some pervious owner so someone did. My sister who is touchy about smell of cigarette smoke has never commented on it smelling like smoke which I'm sure she would have if it had a detectable odor.
If someone says it is non-smoking owner and no pets it probably is at least during their ownership. If you are truly allergic (as in physical reaction that responds to ant-histamine drugs) it is on you to dig into the details you need to know. The feather pillows and/or sanitizer used on them in motels causes my eyes to become blood shot and gummed up with eye boogers, my nose to run and my sinuses to fill up like the soo locks. Guess who has the responsibility make sure those are not feather pillows on the bed?