I acquired a second hand Rotex 150 and a CT11 about 3 years ago. Both had mainly been used for Solid Surface finishing. Both were dated 2002. They were a little scruffy, but not that bad considering they were 8 years old. I was assured that neither had ever been back to Festool for any service work.
I replaced the filters in the CT and brought a new 27mm A/S hose for it, and put a new sanding pad on the Rotex.
Both tools still work well and have never missed a beat in my 3 years of ownership.
It is a bit of a lottery buying second hand tools, but it can pay off!
Admittidly, since I got these 2 tools, it did start me down the slippery Festool slope and I have gathered a lot of momentum.......!!!!
The rest of my purchases have been new tools, but if a good second hand deal came up, I would not hesitate in buying second hand again.