I am fairly sure this is a common one. The use of describing used goods in MINT condition is not really a scientific measurement with a fixed baseline, or is it?
Let's look at the WIKI
So a mint condition (used) computer would be one as fresh the day it left the factory? No visible usage markings (scratches, dents, scuffs, ground in dirt, PVC cable burns, yellowing, fading or teeth marks etc).
My recent experience is that I bought a computer stated as "The unit is in MINT condition in its original box. Works nicely. Perfect collectors item." The pictures provided manage to exclude some of the above mentioned visible defects. Additionally the item didn't work either.
Initially the seller claimed not to have stated the condition as MINT, however when reconsidering his own words decided that as a non native English speaker then MINT only means used but a good condition considering the age.
Let's ask auntie Google about this. See the 1st and 2nd hits:

I'd also like to hear your horror stories on the misuse/overuse of MINT condition.
Let's look at the WIKI
Mint condition is an expression used in the description of pre-owned goods. Originally, the phrase related to the way collectors described the condition of coins. As the name given to a coin factory is a "mint", then mint condition is the condition a coin is in when it leaves the mint.[1]
[h=2]Variations[/h]The term mint condition may be used to describe a variety of collectible items, including action figures, dolls, toys, stamps,[1] records,[2] comic books and similar items.[3] The term may have a slightly different meaning in each case. For instance, when describing trading cards, "perfect" condition is used to describe the condition as it is when pulled from a pack, while "mint" would be new but opened. Similar graduations of mint condition exist for other collectibles based on their specific characteristics. For example, a postage stamp may be mint or mint never hinged.
So a mint condition (used) computer would be one as fresh the day it left the factory? No visible usage markings (scratches, dents, scuffs, ground in dirt, PVC cable burns, yellowing, fading or teeth marks etc).
My recent experience is that I bought a computer stated as "The unit is in MINT condition in its original box. Works nicely. Perfect collectors item." The pictures provided manage to exclude some of the above mentioned visible defects. Additionally the item didn't work either.
Initially the seller claimed not to have stated the condition as MINT, however when reconsidering his own words decided that as a non native English speaker then MINT only means used but a good condition considering the age.
Let's ask auntie Google about this. See the 1st and 2nd hits:

I'd also like to hear your horror stories on the misuse/overuse of MINT condition.