My first TT was a 1996 Mallard 31T bought used from a construction company that used it as a site trailer in a northern community while they were building. We picked it up for a song in 2009 I think (maybe 2008). The only issue we ever had with it was all the connectors on the water lines had been loosened and they leaked when we pressured up the system for the first time and the awning was almost completely rotten from years of being in storage outdoors through Saskatchewan summers (+30 and sun) and winters (-40 and wind!). Not a single other problem with that TT.
We camped three or four seasons in that until DS came along and we didn't have room for his bed and "upgraded" to our Zinger ZT33BH last year.
Issues with it in our first season:
-Main slide quit working on electric
-Furnace cycling (turned out to be completely improper installation)
-Fresh tank broke and fell, ripping the propane lines off the underside
-Lots of little things like doors not closing, drawers not staying shut, etc
-Completely counter-intuitive electrical wiring where there are too many plugs on one breaker and only a couple on the other
-A 40 gallon grey tank with the only thing connected being a sink that's barely large enough for hand washing
-Front entry steps seized up so bad DW can't get them open, and I struggle with them
So, to say you'd be better off going new...well, it's kind of a crapshoot either way. The only saving grace going new is warranty.