I agree with Godfather...I have a hard time buying the Pavlov theory on this issue. I mean, if you are in the cage more often to handle, clean, change water, etc. I think there's less likely a chance they will associate you with food.

I feed in the cage - of course I use carpet. If you have a loose substrate I think you should feed outside the cage...but then again my Kenyan Sand Boa is on crushed walnut shells and I just lay a piece of carpet on top and feed him inside