A/c Stinks

Does anyone else have this problem? Whan I start the air conditioner the air coming out of the dash stinks so bad that I have to open all the windows for about a minute to clear the stench. It's REALLY bad. After two trips to the dealer, under warranty, I was told that the evaporator is constructed in such a way that moisture is trapped on "ledges" on the evaporator. This water then grows molds and mildews that stink when the fan blows the mold/mildew into the car. The dealer attitude is too bad for you, we won't fix this
needless health risk by replacing the evaporator with one of a better design.
Does anyone else's Focus smell bad when the A/C starts up??