Kinda depends on what you are dealing with. Certainly, you want to wipe out/destory mold. If it's a light smell you might be able to get away with Febreze. But, if it's anything of substance, you should use an Ozone Generator.

I stated collecting arcade machines and picked up a few "funky" ones. Picked up an Ozone Generator for less that $100 and it knocks all the smell out of them in a couple of hours. It also works good for cars too if you get something nasty in your car. Totally worth the money IMHO.