We bought a 2002 Land Yacht 30 in nov 2005. A boat dealer took it as a trade-in. 59 000 km ( 37 000 m). Great shape, very clean. The previous owner changed the oil every 6000 m, not great but enough. The MoHo was used regularly. But the dude never changed the oil on the genny because of the low hrs (32). Paint was peeling on the oil filter... I did spoke to the guy, an old man of German origin. These people keep their things CLEAN!
I checked everywhere for sign of water ingress, none. No smell of humidity. Tire wear was even. The engine started easily I put in an offer two days later, requesting that all maintenance be completed - winterising, lube oil and filter, genny. I drove the Moho home, 300 miles and I am absolutely happy with my purchase. It drives like a car! Fuel consumption was close to 10 m/usgal.
One reason I bought it is that a buddy of mine has had one for three years and he is very happy with it. We knew the RV for spending some time in it. No slide but it is a high-end product, not an entry level. All materiel is high quality. Real wood, no laminates. Well worth the money.
So check for signs of water ingress and ask for maintenance records.