A different perspective and a drop of knowledge...
...actually
very different it seems from the others in this thread:
Though I have jeans that I wash as frequently as most of you, I also have jeans that I wear frequently but wash once every 3-6 months. Actually, I have two pairs that I haven't washed yet and they are going on 10 and 13 months respectively.
Gross? Depends on who, but I can appreciate if you say so. Unhygienic? Not really...lots of studies to support this especially if you consider how often you wash your couch for example.
Anyway, if you can get past this part...I offer some insight:
With the popularity of the "worn or distressed"-look of jeans, different washes and treatments were introduced 5-10 years ago to the denim market (think Seven, Rock&Republic, Paper, Diesel, Parasuco). Because each brand could offer almost limitless styles, washes, and looks, this led to the premium denim market which were highlighted by various unique designs and designers with higher end pricing. Naturally, consumers and companies alike realized that nothing beats your pair of Levis that you've had forever and have worn in like a glove...stretched perfectly where your knees are, ripped where you constantly dragged the cuff on your shoes, discolored where you kept your wallet, or sweat stained from havng your hands in your left pocket all the time. Brands emerged (my favourites are Nudie, Imperial, and Farmer) that offered "raw" and "selvage" denim jeans, which are intended to be naturally "worn" and rarely washed as this breaks down the material in a negative way. Raw being denim material that is dyed but not washed anytime during the manufacturing process. Most jeans are washed in chemicals either before or after the sewing process to break down the fabric and make it softer and more comfortable. Selvage is a more expensive and higher quality denim fabric because it is thicker than standard and made from double looms instead of single looms.
So, if you are a denim affcionado like me, it is more important to wear your jeans then to wash them, especially if you started with raw denim and want to create that perfect pair!
Don't believe me? Trust me, there are many others out there like me..check it out...
http://www.nudiejeans.com/thisisnudie/takecare.php
http://www.imperial.st/users.html
http://www.farmerusa.com/care.aspx