Is a water stain on ceiling a deal breaker?

I am shopping for my first motorhome. Walking through many units at PPL today, I saw many with water spots on the ceiling. They were especially evident on those with carpet-like ceilings. If I smell mold/mildew or even a newbie like me can detect more extensive water damage, I am high tailing it out of that coach. Should I also walk away if an otherwise promising unit has limited ceiling stains (for example, near skylight, wall or slide)? When I push on such areas, should they feel really hard (like wood right under ceiling fabric) or can there normally be a bit of give (like maybe foam board behind that ceiling fabric)? I'll happily pay for professional inspection, but I'd like to screen out as many problem units as possible myself?
Thanks in advance for any and all advice,
Windy