If you disable it and do a Disk Cleanup it should clear out temps. As the Guest account is disabled for a reason far better and more secure would be to leave the Guest account permanently disabled and create a new Limited User account for others to use. They are easier to control and check from within an Admin level account.

I've never heard of that happening automatically, sorry. That would happen if you created a limited user account as I suggested earlier and then deleted it afterwards when whomever was using it had finished. The guest account can't be deleted but a limited user account can.

Best read the tutorial and by limited user I should have said Standard User...that's what they are called in Vista, sorry, my error.
How to Create a User Account In Vista

The Guest Account is hidden but should be accessible in Control Panel > User Accounts if you are a user with Administrative authority.

We all have our oops moments, believe me.

Winter, it sounds like you're concerned about multiple people logging on with the guest account and seeing what's left over by the previous user. In that event, you might want to create multiple guest accounts (you can create as many as you wish).

You can also institute further restrictions using the Parental Controls. Remember, they're not just for kids.

There are some more extensive things you can do with group user policies, but this is only in the Professional, Business and Ultimate editions.