You are right about the VFT being mostly self-cleaning while outdoors, Bob.
My six year old VFT lives a transient life in three stages. It goes
outdoors in the spring, indoors in the fall on a windowsill and (usually)
spends its dormancy in the fridge. While the weather seems to take care of
cleaning the traps outdoors, indoors the VFT is still very good at trapping
any flies that wander inside and the detritus left over after a trap
re-opens can be an unsanitary source of problems to the VFT and possibly
your other plants. If not that, then it just ain't pretty. In order not to
re-activate the trap (we must resist the temptation to play with our VFTs),
I give any bug carcasses a shot with a stream of water from a mister, or a
quick snap with the end of my tweezers. You get very good at this.
I don't know what happens with the VFT when it is in the fridge.
Rand