Thanks to you all for replying. I guess I should have clarified in the initial post that I wasn't talking about body odor but a chemical smell that I wondered was maybe a scent of the drug itself or a byproduct of the drug that those who have been around can tell when they smell it.

A kind person sent me some links in the background and I think Stevie is right. Apparently when the body is stressed (whether from dehydration, lack of sleep, malnutrition, extreme stress) sweat can smell "ammonia like." Also glad to confirm I wasn't the only one to have asked that question over the years.

A "body odor" or hygiene problem never popped into my mind since I have never encountered that so I didn't realize I should have clarified for fear of offending.

I wasn't saying the people I was standing by smelled like they hadn't had a bath in weeks I was saying they had the same strange chemical smell I get from being around my husband when he is using (different than his regular sweat smell that I know well after 16 years). And I didn't necessarily say it was a bad smell, just something different like standing next to someone who has spent the last day in a smoke shop with incense burning all day long.