Dress pants... they're black so I wear 'em at work. They always have a bad smell to them. It's not a usual black smell... it's unique. They smell like this even right out of a wash.
:(
Add an essential oil or something soft (lavender) to the cycle. Set the cycle to hot if it isn't, and make your washer do a regular cycle. Those 'water efficient' washers which do it with a teacup of water (literally) cannot possibly really clean your clothes.
Then dry it in the sun, make sure it airs well. See if that helps. If it bugs you
so bad, try bleaching them and then staining them black (to compensate) or something drastic.