Stinky teenagers

I don't have any tips for you, but I will tell you that you (or your son rather) are not alone.  My wife is a high school teacher and I help out at a lot of events at the school and some of the young guys there stink to high hell to the point where I want to be nowhere near them.  Oddly enough the girls cover themselves in so much perfume that it's hard to breath around them as well. 

Maybe some dryer sheets in his shoes?  Cologne on his clothes?  I don't really know.  Good luck.

may be a diet issue.  as to the wash use detergent with baking soda

This may be a starting point

http://www.naturalnews.com/004417.html

I second this hypothesis. If it isn't external, that leaves internal...

Adolescents tend to smell strongly. I would second the idea of having his doc check him out, in case there is something more to it, but I always think about the patient I had who told me that she hated her school in part because "it smells like hoagies and puberty".

As for clearing the funk, I might try some "Sink the Stink" - it's available at scuba shops, and used to de-funkify neoprene, but it would work on other things as well. I have renewed several pairs of Vibram shoes that reeked even after being washed with Febreze several times and dried in the sunlight. Roughly $10 a bottle, and lasts for a while.

For some reason kids seem to stink more at puberty, but not to the extent that you are talking about.

I was a bit of a stinker.  I did 2 sports (cross country/tennis), one before school (cross country) sometimes at lunch (cross country), one after school (tennis) and then another training session after that (tennis).  In order to keep the odors down I showered 2 - 3 times a day.  One after morning run, one after lunch run (if I had one) and one after last training session when I got home.  I constantly struggled with Athletes foot, so I went through 4 pairs of socks a day.  It kept my shoe odors down though.  IMO, spend the money on good socks and change them out frequently.  I have only found this to be more and more true as I got older (and started backpacking).  Back then I had about 20 pairs of thorlos, but there are probably better brands now.  Even today I'll go through 2 - 3 pairs of socks in a day.

I'd go through an equal number of clothes per day also.  If there is nothing else wrong then the stink most likely comes from build up.  I mean I stunk after one use, but a second use was a biological weapon, so my mom made sure I didn't do it.  It was just gross too cause the shirts were so soaked in salt that they were semi hard. so on the days I had 2 runs, I had 2 sets of shirts and shorts.  For tennis I just changed shirts between lessons.  one use = one wash and that helped keep things under control.  I carried around a lot of clothes.

So basically change more often, wash after every single use, and shower after each session.

I agree with other posters that diet could very well be doing it too.  I know even as an adult that after I eat certain foods, you can smell it on me within a few of hours.

If none of those do the trick, then hit up the doc and see what he says, cause that just isn't normal.