You will probably find that the dealer will blame the loose gas/sink fittings on the manufacturer as I doubt those are things that get checked at a dealer. When I bought my TT, I do recall the salesman pointing out to periodically check all fittings for continually being re-tightened as travelling vibrations will eventually loosen those.
Just seems like dealers are mostly interested in RVs that show up on their lot in good "viewable" condition. So, they would do a walk-around to make sure it looks like it is not damaged from transport and will be a good unit to get sold quickly. Do they do independent PDIs when they come in to make sure everything is tight and working and ready to go? I seriously doubt it.