There is practically no quality control on units at the factory. All systems are not checked before shipment, that is up to your selling dealer!! Water tanks, water lines, plumbing fixtures, A/C and furnace are not checked until the unit is sold. You must have a good relationship with your dealer, and demand a very slow thorough walk thru and pressure test of all plumbing. Make them fill the water tank and test for leaks and operation before you leave the dealership. Also make them hook up a city water connection and test that. Test the A/C and furnace thoroughly before leaving the dealership also. Put water in the gray and black water tanks, check for leaks, also check for proper operation of the dump valve. You might also check the date of manufacture on your axles. Many units had grease seals leaking grease on the brakes......massive problem on many units and there was no recall.
Maintenance is a never ending ritual with all RV's regardless of brand. Sealing all joints is a constant must do. Water intrusion causes delamination on all brands! Airstream makes the only trailer that is probably a 100% sure bet on quality but their price is profane. You get what you pay for. Quality does not come cheap.