The foolish buyer trick I've seen more often than others is the "It comes
with a fresh annual, I don't need a pre-purchase inspection." approach to
airplane buying.

Aargh.

We had an estate auction in this area recently where 4 vintage aircraft were
sold. Unfortunately (for the buyers), the rules of the auction prevented
anything more than a logbook review and a cursory look at the aircraft. All
4 aircraft sold during the auction at reasonable prices considering these
aircraft had sat for a couple of years and the logbooks *probably* were not
in the best of shape. Although each of the aircraft came with a fresh
annual. ;-)

It is 3 weeks later and three of the four aircraft have not left the nest.
The fourth aircraft did go home with the new owner after a blown crankshaft
seal was replaced. I can't understand how the annual didn't turn up a blown
crankshaft seal.

One of the aircraft still on the field had 50+ squawks when the new owner
gave it the once-over. Now, this was an ongoing restoration project and a
few squawks should have been expected but over 50? With a new annual? Not
acceptable.

Another of the aircraft still on the field wouldn't pass a run-up. Why? It
had been filled with autofuel some time back, not flown or run for a while,
and the fuel system was badly gummed up. Oh, by the way, there is no
autofuel STC for this airplane. Again, this airplane had a fresh annual.

The other airplane still on the field hasn't had maintenance related
problems, so I guess the owner is probably happy with that. He's probably
not happy that he ground looped it on his first landing. It is undergoing
some minor repairs at this time.

Another foolish buyer trick is buying a fixer-upper. Generally, an
airplane's value is LESS than the sum of its parts. Take a $30k C-172 or
Cherokee, add new paint @ $8k, a new interior @ $5k, a new panel @ $15k, an
engine overhaul @ $15k and you still have an airplane worth $50k or less
despite the $70k+ you've invested.