The worst is that cheap food usually tastes great... :)
Cheap food typically gravitates towards a combination of these 2 ingredients.
Cheap food tastes great until you try it next to food made from high quality ingredients and prepared the way you want it. For example, I used to like white bread. Since getting used to the different flavors in multigrain bread, white bread is too boring. (By multigrain, I don't mean the refined stuff being labeled as multigrain. I mean the kind in which you bite into a chewy grain with a nutty flavor.)
Here's the deal, though:
You could conceivably add the right chemicals to a pile of offal cooked in a skin of some kind and it'd taste like a gourmet sausage. You might have in fact eaten such a thing. It's also common to add flavorings such as "grandma's special recipe" or that from a dude in a coat from Kentucky. All these things make us think that something tastes good, which as also commented in this thread translates in your brain to mean: "hey, this is good for you, have more!".
But the reality is, what you're eating is almost certainly mechanically reclaimed meat (where carcasses with so little meat it's almost pointless to continue cutting are put through a machine which crushes, juices, minces and turns out a slushy type 'meat' goo). and MRM is the place where salmonella and other friends live. It's also not really meat: there's plenty of cartilage (aka 'gristle') and such that is cut so small, you actually ingest it. It doesn't cook properly, and it's not really good for you to eat- you just pass it. But if it's carrying salmonella or e-coli... I hope you didn't have something important to do for the next couple weeks.
Also, the nutrition recovery from such a meal is incredibly limited. You feel bright and happy for a short period (the msg et al) and then you have a come down, a craving, and want some more- for that high again. So in fact, what you're eating is a bunch of mind-altering chemicals ontop of a bed of processed waste.
Food shouldn't be like that.
Food should melt in your mouth and be an explosion of flavor and something you genuinely feel excited about. It should be, you have a meal, which provides you with some instant energy, and also some which is "slow-burning". Brown grains (rice, some wheats, etc) are great for this. You will feel full and energised for longer periods.
Cheap base foods are cheap because they are often subsidized (e.g.: corn) or because their most common consumer is the cattle, pigs, chickens etc that you want to eat. This has given a false sense of price - people expect all food to be as cheap. So supermarkets etc will look to find ways to make everything else like it. So you'll see battery farmed chickens, who are so close together they often aren't able to stand up; You'll find chickens who are injected with water to make extra weight. (yeah, that chicken you just bought? probably a pound of it is water. You just paid chicken price for water).
Good food is good because it provides great nutrition, is often respectful of the environment and is sustainable.
Everything else is just yet another sign of man's dominance over everything else.
(BTW, no, i'm not an enviro-hippy, it's just that i refuse to eat crap if i can help it- why put yourself through that kind of thing when there's so much better choice out there?)
taste cells on the tongue contain chemoreceptors. Those turn chemical signals into potential - i.e nervous system signals.
Since normal food has normal type chemicals, whereas manufactured, msg type food has make-it-taste-nice chemicals. Those are two different sets of chemicals and so, yes. food which tastes good is different from thinking it tastes good - they activate different chemical pathways and trigger different receptors.
Taste is supposed to identify healthy and needed substances vs. deleterious or poisonous substances, so when this is subverted artificially, it feels like a trick to me.
That's why we have taste buds for it.