I have a neighbor whose garage is as clean as most peoples houses. His hand and power tools are immaculate and his 3 year old TC29D looks like the day he bought it.
I have no problem with the occasional "lend out" of a tractor/attachment to someone like this. You know if the tractor starts to make a strange noise he will stop it right now and figure out the problem. The equipment will also come back cleaner than when it left.
But for those guys whose equipment hasn't seen a storage shed or an occasional bath sorry, I can't sleep at night if I lend it out. I know I may offend some folks here but the way you take care of your tractor/equipment is an indication of how you might take care of mine when you use it for a couple of days. I'd much rather do the work for you for free, or perhaps a cold beverage or two, than lend it out.
I started a similar thread about a year ago. The responses were about the same. Lend out the tractor on a rare occasion to someone who you know is a tractor guy and knows how to care for the equipment. You don't lend out your $20,000 compact tractor to a guy whose only contact with power equipment is a 21" Toro push mower.