Jay Honeck wrote:

3. Observe the FBO. How's the place look? Are there people around?
Check the magazines -- are they five years old? Use the bathroom. Is
it a pit? Is someone taking pride in the condition of the place, or is
it a dive? All are indicators.

Good advice, except for most of the above.

I happen to know be very familiar with a high-quality FBO who operates
in a city-owned, badly maintained, RENTED facility, built in 1936. His
aircraft are in great shape, and his mechanics are high-quality on all
levels. The place is orderly, neat, and organized, but the building is
a pit.