I've been seeing avocados with grill marks and recipes for heated/grilled/cooked avocados. My (limited) experience with that is that they don't do well at all when heated, getting watery, bitter and generally ruined. Is this anecdotal experience common, or am I missing out on some good grilling? I can't bring myself to try it without a lot of input. Avocados are just too good to ruin.