When I had my music store I sold a lot of those Dean Markleys. Mostly a model that was bigger than the one above. One of the best sounding amps on the market at the time, Do they still make them. I regret not keeping one for myself. I never had anyone bring one back.
The worst amps for returns were Marshall Valvstates. All the controls would bonk out after less than a year. There was a little Samick 10 watt practice amp that was a dead ringer for a Marshall tone at 1/2 the price. They also developed scratchy pots. They used the identical parts.