In general, I would agree with you. (Although, as long as they discuss it with you before purchasing the unit, I don't think it HAS to be in the ad itself.)
(Also, I would be more forgiving of a lack of such an admission if the work was done by the manufacturer. Replacing something small that fails, such as a capacitor or a resistor is not that big a deal, IMHO, especially if done by the manufacturer.)
I would also think that any upgrades to the unit should be mentioned as well, and especially if they were not done by the manufacturer.
My two cents worth.
(Also, I would be more forgiving of a lack of such an admission if the work was done by the manufacturer. Replacing something small that fails, such as a capacitor or a resistor is not that big a deal, IMHO, especially if done by the manufacturer.)
I would also think that any upgrades to the unit should be mentioned as well, and especially if they were not done by the manufacturer.
My two cents worth.