Adding instant to stretch mashed potatoes
Using bread conditioner or ice cream stabilizer
Corn Bread Muffin Mix
Prepared Tartlet Shells
Microwaving Baked Potatoes
Adding gelatin to stock
Liquid whole eggs
Well, what about them, Benway.
In each case, if it helps the cook produce the best possible dish, then using them is not cheating. In many of those cases, however, they will not contribute to improving the final dish. So it's not a question of cheating; it's a question of serving lower quality food. Let's take them in order:
Adding instant to stretch mashed potatoes. You pretty much said it here. The aim isn't to improve the taste or texture, it's just to creater greater bulk. Doesn't apply to what I said.
Using bread conditioner or ice cream stabilizer. What, exactly, do you see as a problem with these? I don't get the objection.
Corn Bread Muffin Mix. I don't see the slightest problem with this. I happen to dislike the end product from these mixes, because they're more like cake then corn bread. But that's just my taste preference.
Food Coloring. We eat with our eyes, first. If color is an important part of the presentation, what's wrong with using food coloring? Good grief! We just celebrated a holiday that depends on food coloring for its very being.
Prepared Tartlet Shells. This one doesn't even deserve comment. Prepared shells are exponentially better than anything that most home cooks can make (me included). So are you saying I should use second best (my own) when a better product is available, just so I can brag about them being homemade? That makes no sense to me at all.
Microwaving Baked Potatoes. That's not cheating; it's choosing an alternative cooking method. If you like steamed potatoes rather than baked, then there's no problem with using the nuke instead of the oven. This, once more, boils down to a quality issue.
Velveeta. Lemme see. We're talking about a product that melts easier, produces a smoother sauce, and, to many people, tastes better than actual cheddar. Using it is a problem how? Oh, yeah. It's not "real" cheese, so is obviously cheating.
Adding gelatin to stock. Why would this even be necessary? If you've made stock correctly it already has all the gel it needs.
Liquid whole eggs. I don't even know what these are. Does using them affect the taste, texture, or consistency of the final dish? That would determine whether or not I'd use them.