Perhaps the first reason that comes to mind when it comes to choosing between new and used is the economic one, but in reality there are many others that can guide a person in the choice of used, for example the passion for vintage campers (and I guarantee you that there are many people attracted by this type of vehicle), or the search for simple mechanics (especially to limit electronics), or even the preference for functional and inconspicuous fittings .
Even if I have a specific article planned, and as soon as it is ready I will insert the link here, a simple reminder of important things to evaluate for the purchase of a used camper I want to anticipate it for you:
keep in mind the circulation restrictions Euro 0, 1, 2 ...
check the administrative documentation of the vehicle, the registration, the revisions, the coupons
have the obvious checks done on the mechanics , engine, brakes, mileage
consider the age of the batteries (engine and cell) and their condition, check that they charge correctly (alternator, 220v cable, solar panel)
the tyres , consider that beyond the kilometers travelled, the change is recommended (I would say highly recommended) every 4 or 5 years , and the expense is not exactly negligible
check the operation of all the systems : fridge, hot water boiler, heating and air distribution (it must come out of all the vents), stove, if there is a photovoltaic system check that it works
check that the connection of the camper to 220v (using the appropriate cable) works and that the internal sockets work, also test the fridge at 220v
plumbing: working pump and water from all taps, don't forget to flush the toilet
bathroom: shower tray and sink NOT cracked; toilet intact and, if orientable, it must turn well; try to insert and remove the cassette, the operation should be smooth
if there is a LPG tank , check that it is approved and written in the booklet, check the expiry date (it must be replaced at 10 years there is NO inspection, the cost is not indifferent, if you are not interested in the tank, consider that you will have to restore the system of cylinders, less expense than changing the cylinder)
if there are gas cylinders , check if there is a selector to switch from one cylinder to another (useful) and if there is an approved crash sensor (for example the Truma one), necessary to travel with open cylinders (think about heating the airframe while traveling in winter)
clear water tank : where is it? Inspect it to see if there are any algae stains or dirt inside
gray and black tank (if the toilet is nautical) : check their position, if they are insulated and heated (necessary for frequent winter use in prolonged outings), check the functioning and tightness of the discharge valves
infiltrations : check from the inside that there are no black lines, mould, swelling, bubbles and detachment of the covering , in the walls, floor and ceiling, in the attic and in the joints between the ceiling and the walls (also inside the wall units), around the windows and portholes, it is useful to spend a few tens of euros for a humidity indicator
infiltrations : if you buy from a dealer, ask for the infiltration guarantee of at least 12 months, if you buy from a private individual, ask (at your own expense) to have an infiltration check