When looking at an older tractor key in on new paint.
Older machines are just fine. I have bought many used vehicles, including my Kubota. Overall condition and service history should be your guide.
Check the oil. Is it black as liquid coal?
Overall paint condition? Has it spent its life outside?
3pt ball joints: Is everything loose and rusty or tight and greasy?
Tire condition? Easy to fix but not cheap if its the rears!
Pull the air cleaner: Is it chocked with dirt?
Is the fuel filter bowl plastic? Does it look clean or murky?
All of these are clues as to how the machine has been used/abused. If the price is right, fixing a few small items is no big deal.
That said, I bought a 9 month-old L3800 off CL with 126 hours on it and it had never seen the service department. Original oil. Caked air filter. Smashed hood. Shattered headlights. Slightly faded paint from sitting out all its life. I got it at a great price and the machine under the smashed hood was like new. Even the dealer was stunned at what I paid for it. Now, it looks pretty darn nice and except for a couple "issues" that warranty took care of, its a really handy and reliable machine. I couldn't run my property without that Orange rascal.
Be alert for a good deal. Be patient. Beware fresh paint (poke it).