What IS that smell?

Have you ever walked in to your house after a day, two days, weekend away and hit a wall of stank? Whoa lord, did we hit one this Sunday. After a good 48 hours away we came back late in the day to an unidentified stench. My first thought was trash. Nope. My second, the dishwasher. Wrong. Diaper pail? Nada. Finally I went upstairs to the laundry room. I opened the door and almost dry heaved. The washer could have been a skunk. I had read front load washers can acquire a mildewy smell, but this was beyond. I immediately ran the sanitize cycle with hydrogen peroxide. This helped (and actually cured the mildew smell last time), but did not quite return the "fresh" indoor air smell we're all used to. So now I am using powder detergent (as recommended by many an internet expert) and running regular washes. If anyone has further suggestions please let me know! 'Till then, an air freshener and a prayer is all I got.