Mine (one of mine) is a daylight alarm clock, it slowly turns on a light for the right time. It is foolish for three reasons:
1) It doesn't actually wake you up, though there is a buzzer option, but using it is annoying since out of the array of buttons on it none of them says "STOP BUZZING"
2) The variable resistor bit and possibly some more circuitry is worn out, so not only does it not come on at the right rate any more, but it also doesn't uniformly do it wrong. Sometimes it only comes on half an hour before wake up time when I told it to do an hour. Once it came on and the automatic turn-off didn't work for two hours, so I ws lying there in limbo thinking it was 8am until 10am. I had terrible flu, so didn't think clearly enough to wonder whether it could be trusted as an indication of the time or not, but helpfully it didn't matter that I was then late.
3) It gains time. I thought all my other clocks (battery operated) were getting slower but then realised the computer and my mobile phone were then also getting slower, so the better explanation is that the clock is getting faster. This is annoying. If I wanted it ten minutes ahead all the time I would set it ten minutes ahead all the time. And, if you reset the time to what it should be, within a few days it is about ten minutes fast again.

Mind you my computer isn't much better, since it still thinks I live in California.

Mine is a little bedside alarm clock. It does the alarm bit just fine, but like yours gains time. I reckon mine is gaining about a minute every 2 days. It has done this since we bought it (although it took us a long time to work it out since at the time it was the only clock in the bedroom). I'm astounded that people can still make and sell clocks that don't actually function as clocks.