Crotches will smell at some point without packer or anything as well. So in that sence I've never had a problem. My stp as started to retain some smell, this is mostly from sweat and not from urine. If I sit to pee halfway throughout the day I will smell it. But as long as I don't drop my pants it's fine.

I wash it with soap and water every evening and boil it once in a while to sterilize (note, you can't boil every stp, you might ruin some with it)