I don't mean to disparage FBO/flight school maintenance in general-
I guess my main point was that  the planes offer more unpleasant surprises than the instructors, on average. At least that's based on my experience: 5 instructors and about 6 or so different aircraft during my 2 years working on my PPL... liked some instructors more than others, but felt they were qualified to teach, regardless of what their resumes might have said.
As Hagar noticed, the annoyance of high CFI turnover is the biggest problem I had with that school... cost me hours of review, and yes, I lost a couple that I really clicked with, and had to adjust to a few that were not quite "on my wavelength".
  I'd advise a PPL hopeful who can't knock out the whole syllabus in a cuple of months to find a retired person or career instructor who will stick with you- young CFIs eager to jump off to the next rung on the ladder are often excellent pilots and instructors, but they don't stick around long.

On the other hand, as far as the aircraft go, during that period I had:
One starter failure
One smoking transponder
Two incidences of finding tools under the cowl or clamped to the cowl
One badly damaged brake line (noticed, fortunately, pre-flight)
Numerous radio and intercom problems
One landing light failure (the one time I arrived solo at sunset, of course)
Missing aileron balance weights
Inop flaps
Inop vacuum systems
Useless nosewheel shimmy dampers, usually coupled with badly worn tires and underinflated struts

... that's the ones I remember offhand...but my point is made.

We have to bear in mind, of course, that these are not things you'd find out about, necessarily, by looking at the maint. logs, but I mention doing so mostly because if the aircraft owner or operator is reluctant to produce them, you should walk away (or run, maybe).
  Doesn't matter if you know how to interpret the data- they should be willing to reveal all
If they won't, consider that a "red flag".

A Certified Flight Instructor's qualifications need to be broken down backwards.

Even this link  http://www.gleim.com/aviation/flight_ground/fgreqs.php ; doesn't give the whole picture. For example.. it just quickly mentions that one of the first requirements is a commercial or ATP rating. Those in themselves are rather involved accomplishments. A commercial rating itself has, as a bare minimum, 250 hours.

Basically.. A CFI is an instrument and commercially rated pilot; demonstrating a certification and aptitude for teaching; having passed appropriate written, oral and practical testing.

There's no doubt in my mind that path to CFI-dom has evolved into something that accommodates those using it as a step along the way to some other flying career. Ideally, it should be a viable career choice on its own. Unfortunately, it is not.

I'll bet there's an interesting story about how FOI made it into the requirements. It is logical, as you'd be a "teacher", and governments love their paperwork and certificates.  I've heard the test isn't any more difficult than any other, FAA writen exam. You gotta admit, they have a "civil service test" air to them.

I was a substitute teacher at a community college, right after graduating. I just called up the office and asked them to re-certify me, as if I'd be coming back to substitute again. That info on the college's' letter-head let me skip the FOI test.

I wish I had accurate (and fond) memories of my very first instructor. Iwas all of 19. He ran a slip-shot little operation in Escanaba, Michigan. His son still operates a private, grass strip on their property, just outside of Gladstone. He might even be dead now.. Last time I heard anything about him.. was when he flew drunk and landed on the freeway near the airport 

The instructors (and the guy who ended up being my mentor) I've met, flying out of KOSU have been wonderful. Ohio State University runs their Aviation Department out of that airport. In fact.. they RUN the airport. Most all the instructors that filter through the three clubs at KOSU, are fresh graduates from OSU's Aviation Program. High standards permeate the whole area; and it's a very tight fraternity. It's actually the busiest airport in Ohio, as far as take-offs and landings go. There are also two medivac operations there; and several corporate hangars. I'd guess that there are at least a dozen corporate jets based there. Even the tower guys are part of the "gang". Our club lets them access the internet via our wireless router so they can keep themselves entertained on slow nights.

The instructor who got me through my instrument rating ended up taking a job flying a Rockwell Commander for a company that does USGS, aerial photography. One of HIS instructors flies a Citation for Honda (won't be a Citation for long     ). The day I passed my instrument checkride, we got to go sit in that Citation and just talk pilot stuff (I got left seat in honor of my new rating).

Sorry.. got  to rambling...