The operation of the dimmer is correct in that position moving the dimmer slider up brightens the lights down dims the lights. You can reverse the wires and it will work exactly the same way.
Bmw E90 Reverse Light Switch Replacement E91 E92 E93
Light switch reversed on off. There are no on or off markings but the light that stays constantly on is controlled by one switch that is located on panel with 2 other switches. However smaller switches have traditionally been mounted the other way up so switching down will switch it on. The switch and dimmer work fine but the operation of the switch is reversed. A light switch is a single pole switch. Look at the switch. With large switches it is considered should anything drop on the switch and operate it then it should switch it off.
Took picture and my wife double checked 3 black wires on top right. Went to home depot and bought new dimmer boucht cfl compatible dimmer as tried cfl floods before and they only lasted a few weeks hooked up same way as before. Clearly with the rocker switch little is likely to fall on a switch and move it. So all breakers are down for off. Moving the switch lever to the up position turns the lights off. Moving the switch lever to the down position turns the lights on.
But you are describing a three way switch and the other one was used to turn the light on or off which reversed the function of the one you usually use. The only way to change the orientation of whether it is on or off is by physically reversing. Dimmer in kitchen 5 dimmable flood lights went out. The switch that suddenly reversed itself is a single switch thats on a different circuit from the one that wont turn off. The other 2 switches appear to either do nothing or they are dead. Hj mar 22 2011.
With the switch mounted in the upright position. If it is a single pole and not a decora style it should have on and off printed on it and would be impossible to reverse the function.