A few words about instrument condition...
The condition of an instrument can be highly subjective. Something that looks very good to one person, might appear only fair to another. Furthermore, a salesman is always tempted to speak highly of his product. Nevertheless, I strive to give an objective, honest description using the following terms:
Poor: Could have missing or broken parts, or could be non-functional or marginally functional. It might be banged up or just so old it's falling apart. Not for the professional. A project for a hobbyist, a parts unit, a movie prop.
Fair: Workable instrument, but old or somewhat scratched up. Not dropped or bashed, but probably well scratched and possibly dented. Could have a broken knob or other plastic part. Probably older, and in need of switch contact cleaning or other maintenance.
Good: The average instrument, used and maintained in a professional environment. Functionally solid.
Very Good: Functionally and cosmetically Better than average, usually due to less actual use.
Excellent: Very very good. Functionally perfect, smooth operation. Cosmetically short of like new due to visible signs of handling or use.
Like New: If you put it on the bench next to a brand new unit, it would not be immediately obvious which was which. It might have fingerprints, or a very light scratch, but it should still retain it's factory fresh look and feel.
New: New is new.
Along with the overall condition, I will point out any defects, missing parts, etc. The best equipment has the shortest description.
A few words about age...
While condition is subjective, age is not. Many popular instruments were in production for ten or even twenty years. Who would buy a Honda Accord without knowing what year it was made? With test equipment, age does matter. Potentiometers wear or get dirty, capacitors dry up, switch contacts get noisy, etc.. Every production revision is generally an improvement. With technology, new is good. Usually I try to report the age of an instrument based on component date codes or serial number.
A low price is great, but I don't believe you can simply say that an HP xxx is worth $$$. I often pay extra to get the better unit, because I think it's worth it. That's why most (not all, there are some rats mixed in) of the equipment listed is very good or better condition. My goal is to provide value at sensible price. If you do it right, buying used test equipment makes a lot of sense.