I got stuck in the flood traffic going uphill and had to ride my clutch for several minutes due to an idiot 2" behind me. It started smelling really bad then clutch went out. Had it towed to garage. They drove it several times and said it was fine. I picked it up and drove it just fine but it still smells. Not quite as bad. Is it the slave cylinder. Should I be worried. How long will it smell.
When you have that smell, it is the clutch friction disk which you're smelling, not the clutch slave/master cylinder, nor any of the other mechanicals at that. When you have "that smell", you have overheated your clutch components and they have burned somewhat, causing the smell. When this happens, there is damage to the clutch friction components, but how much damage is done cannot be known without tearing it all apart and inspecting.
If it is working now and seeming to do so without ill effects, I'd not worry about it too much for the time being. Just understand the lifespan of the clutch has been shortened, but by how much is anybody's guess. Continue to use it in good health until it no longer holds at all (starts to slip). At that point, you'll know it's time for a replacement.