Smell might be harder, depending on where it's coming from. If it;s coming from the sticky, then cleaning make correct it. If it's coming from inside, it becomes harder.
I have had my two sets about 25 years, and they still smell pretty normal. They do get sticky based on how long it have been since someone spilled a coke on them.
He said STINKY. Not sticky. Give your eyes a rest man, you've been working overtime on here.
You can usually get the pads off of more decent headphones, if you can then the solution becomes easier, just make sure they're dry before they go back on!
Otherwise, you could always try 'Febreze' or your American equivalent odour-neutralising spray..?