Macaroni and cheese (Kraft or President’s Choice, especially white cheddar) is still good.
I used to like peanut butter + honey sandwiches and Cheez Whiz + Miracle Whip sandwiches when I was young. Yuck.
Still good:
Kraft macaroni & cheese
powdered Nestle Quik–my mom & dad would add only about half of the powder than the container says to do. To this day, I love the weak version, but find full-strength chocolate milk way too sweet.
Bad:
Little Debbie nutty bars
store-bought birthday cake
When I was a kid I would eat Campbell’s cream of mushroom every day if allowed. Today I could not even think about it.
But I still like Kraft mac & cheese from the box.
My palate has only expanded as an adult, not shrunk. I really cannot think of any food I used to like but now dislike. I do notice that some flavors aren’t as strong as they were in the past, though. And I almost didn’t like Diet Mountain Dew, until I got used to drinking diet again.
Holds up:
Corn fritters. My mom used to make these, essentially using a can of creamed corn and a cup of Bisquick, mixed together (sometimes with sugar) and fried/cooked like a pancake. Goddamn, I still love these things. All good all by themselves.
Potato pancakes. Similar to the above (mom, <main ingredient>, Bisquick). Originally made with mashed potatoes, so there was no grain… they were basically pancakes made with a dense potato base. All good all by themselves. I expanded my palate to include thicker non-pancake-like latkes and bubble and squeak and such, adding onion or other things, but no matter the style, I just like having a steaming plate of non-hash-brown fried-potato-whatevers. My last girlfriend came from a latke background and found my appreciation bizarre. “You should have them with apple sauce! Or sour cream!” Nope.
Chef Boy-Ar-Dee pizza kits. Thin crust that realistically can’t be stretched to the pan dimensions stated on the box, ketchupy sauce from a can, horrendous “Parmesan” from a can… still damn good, though not pizza.
Doesn’t hold up:
As everyone else has said, Little Debbie snack cakes. Oh, their new cakes are good (as snack cakes go), but a Zebra Cake at age 10 tastes way different than a Zebra Cake at age 30. “Tasty!” becomes “Did I just bite through a candle for some suet?”
McDonald’s hamburgers. Veg now, but I had this realization before going so… however, I’ll lean on friends who still eat meat. Original reactions to McDonald’s versus regular burgers? Eddie Murphy has it right. Big time right for that age. Holy crap, how can McDonald’s get a burger so fucking right when the ones off the patio are so wrong?
However, getting older, not one of them (or me when I ate meat) preferred McDonald’s over home grilled (or, hell, home skillet-ed) burgers past the age of, oh, 12. They ended up being the meal of last resort on road trips or whatever.
Foods that still hold up for me.
PB&J
Froot Loops.
Foods that don’t work for me anymore.
TastyKake Butterscotch Krimpets - they’re just too sweet for me now.
Cocoa Puffs - they changed them. Now they make the milk turn light brown. That’s just wrong.
The sweetest thing I ever indulge in nowadays is sugary cereals mixed with raisin bran and cheerios. And that’s only if I’m at a hotel whose breakfast selections contain all three, and even then it occasionally is too sweet for me, even though I love the taste of the milk afterward.
I still crave fish sticks, covered in way too much tartar sauce.
To be honest most of the things I hate, now I hated as a kid. And a lot of the things in this thread, Kraft Mac’n’Cheese, Spaghettios, etc my parents refused to have in the house so I never really tried, except at friend’s houses where they where weird not-really-food food.
Still great: homemade Horn & Hardarts mac and cheese
You can’t go home again: Fizzies
I think I was born before there was junk food! Candy bars and soda were about it as far as I can remember. And we never had them in the house.
It wasn’t because my mom was a health nut but rather because after WWII they were just getting started.
I do remember Chef Boyardee spaghetti.
She used to make me a hard boiled egg, smash it up with a fork, salt, pepper and butter and call it “Oh man, oh lady, oh boy, it’s good.” Once she told me I asked for it for dinner every day for weeks.
Campbell’s soup. Can’t eat it anymore. It’s too salty for my taste.
For years my cooking was up to date with the latest trends but as my husband and I get older we are eating a lot more of the meals our parents served. Meat loaf, mashed potatoes, fake goulash, roasted chicken, oatmeal and cream of wheat. Comfort food.
Come to think of it, that’s a trend now, isn’t it? Yay. I’m still with it.
Still good: Maypo, Apple Jacks, Idaho Spud candy bars, Chico Sticks, root beer barrels, Dairy Queen cheeseburgers, Nutter Butter(wafers only), Dilly Bars, Butter Rum Life Savers.
Gone Stale: A&W root beer, Oreos, 5th Avenue candy bars, Stouffer’s Lasagna, Swanson’s TV Dinners, McDonalds “milk” shakes, KFC gravy, KFC chicken, PayDay nut bars.
When I was a kid I LOVED orange soda, and now the thought of drinking it makes my throat close up.
I also used to drink sweet iced tea - my grandmother made iced tea so sweet a hummingbird wouldn’t touch it. Then in military school, I used to make sun tea outside the window of my barracks room, and I didn’t want to spend money on sugar so I learned to like it unsweetened, and now I can’t STAND sweet tea.
Grilled cheese and tomato soup.
I wonder about the Stewart’s Sandwiches everyone has been raving about for years over in another thread here at Cafe Society would be nearly as good today as everyone remembers them.
As for my confession, I still find Spaghettios with little tiny hot dogs good. I buy about a can a year to eat at work.
I thought they were cookies. Haven’t had it since the early 90’s at latest.
I LOVED those as a kid. Then when my kids were young, I had some again.
It took all my willpower not to barf. 
my palate has most definitely expanded as an adult, on the whole. nostalgic foods do not constitute the bulk of my diet.
i need to give newtons another try, i think. i know i don’t like the fig ones anymore but i might still like the strawberry or apple ones. adds to shopping list
looks like they don’t make the apple ones anymore, so strawberry it is!
Canned corn beef hash with eggs nested. I’m sure I’d love it as much as I ever did, but I won’t put it to the test.
YES!
Noooooo!
Maybe not quite on topic, but Waldorf salad was always the most popular Christmas dish at my Nan′s house.
Still love it.
Holds up: Mom’s Tuna and Noodle casserole. Roux, cream of mushroom soup, canned tuna, spiral pasta, baked. I still like it.
Doesn’t hold up: Any pasta in a can. Horrific. Gag inducing. Jarred pasta sauce over freshly cooked noodles is one thing, canned pasta is seriously insane. Yeeach.