For the sake of collecting statistics, I feed my snakes sometimes in and sometimes out of the enclosure. I don't believe that feeding them in the enclosure is going to make them more snappy, but I prefer to feed my ball python in a plastic tub so that dead rat doesn't get dragged all over her substrate and the walls and floor of the tank. Sometimes they will end up dragging it into a water bowl, etc. So, I'll feed her in a tub most times for cleanliness. My bredli and GTP I feed in the enclosure while they are on perches, so there's not really an issue with the prey being dragged around the enclosure. My corn snake I feed in a tub also for the clean factor, nothing else.
I've never been tagged by any snake ever.