I binged on that stuff when it first came out; it was sweetened with aspartame, which “tasted exactly like sugar.”
Unfortunately, not only did it leave a weird feeling in the back of my mouth, it gave me headaches. 
Moxie is pretty terrible.
And rest assured, the Tab that Coca Cola sells now has an Aspartame blend in it. It’s nowhere near as horrible as it was in the 1970’s. It was indescribably bad back then.
d’oh! Repost, this time with the link in working order:
(I had it on the clipboard and thought I hit ⌘-V and instead I managed to just hit V by itself)
as a Detroiter, I’m ready and willing to cut the first fool who badmouths Faygo.
But yeah, diet chocolate soda sounds revolting. Probably why they don’t make it anymore.
I miss Frosh.
In the realm of grapefruit soda, there is also Squirt, invented in Arizona in 1938. It remains popular in parts of the Pacific Northwest.
My grandparents, who lived near Cleveland, owned a set of promotional glassware advocating mixing the stuff with whiskey (unspecified, but probably rye in those days).
I know a fellow Brooklyner who swears by a European variant mixed with dark rum. As an avid summer consumer of both Tom Collinses and gin-&-grapefruit juice, I should probably try it with gin.
No idea why I’m bringing this up in the “worst pop” thread, as Squirt is pretty damn good.
Diet RC? Do you mean Diet Rite? It was fine when it had cyclamates in it, but just like Funny Face, it sucked after cyclamates were outlawed.
No, I mean Diet RC.
Back in the days when we were poor, and had to drink what was cheap, rather than what was good, we had Jolly Good. You could mix and match flavors. We’d always try to get all cola. I hated all the flavored pops.
Note that the cans had bad jokes printed on the inside bottom.
And when you couldn’t afford Jolly Good, there was Little Chute (named for the town, not any gastrointestinal distress). Little Chute came in cases of bottles, and you could mix n match as well. Unfortunately, the “cola” tasted like cola-colored water.
Oh, it’s still around. Big Red. Nasty, nasty stuff. Everyone I’ve ever met who really liked Big Red, grew up around San Antonio. I wanted to like it. It was so pretty and RED. Like cherries. Or strawberries. Not bubble gum. They claim it’s vanilla, lemon, and orange. I taste Hubba Bubba. If anyone ever offers to make you Big Red ice cream, run fast and run far.
Fresca was one of the original diet sodas and wasn’t really marked as diet so a lot of people didn’t realize it wasn’t made with sugar back in the sixties. I think it gets it’s image from the line in Caddyshack when Judge Smayles has convinced Danny not to reveal sleeping with Lacey. Now he’s trying to be Mr. Hip and pals. “How 'bout a Fresca?”
Yeah, Big Red is a super sweet soda and definitely a bit of an acquired taste. I don’t think the flavor is all that bad (I get the bubblegum comparisons, although I taste a lot more vanilla in there), but it’s just too damned sweet.
I’m tempted to buy that 8-pak of tiny Tab cans, just to revisit the good old days. When every secretary sipped the petrochemical tasting Tab while having chain smoking at her desk. Then out to lunch, for a scoop of cottage cheese and a canned peach half, in her office stilettoes and pencil skirt!
Some years ago we bought oddball soda flavors online, a case at a time, from a shop in California. The postage cost as much as the soda, but it was fun! We got some blue soda, blue Jolt (‘all the sugar and twice the caffeine’). It was sweet and berry or bubblegum flavor, and it was OK. What I remember is, after a bottle or two of blue Jolt, we decided ‘let’s paint the kitchen!’ and so we did, up till 5 a.m. painting the walls ‘Orange Sherbet’. 
I don’t know if we could do that again today! Unless someone gave us some meth or crack or whatever it is that’s so popular.
I just discovered I did not dream Choc-Ola.
Dr Pepper came out with a diet chocolate cherry flavor a few years ago for a limited time. I actually liked it. I miss it.
I like Diet Big Red. Gotta search to find it, but it’s good. In my book, it’s similar to a red cream soda. Closest I can compare it to would be Barq’s Red Cream Soda, or back in the day, Fanta Red Cream soda. The former I still see every so often in convenience stores. The latter I can’t find anymore - last I saw it was on-fountain at White Castle in the area, but those all closed up several years back.
I’ve had South African-made Tab and I really have no way to describe it - it doesn’t taste like anything to me, yet I am put in mind of Coke Zero for some reason.
I haven’t tasted one in over 30 years, but Mountain Dew. Obviously my tastes disagree with those of the marketplace. (And, probably, any saccharine-sweetened soda was worse – but I’m giving them a pass here.)
I thought Big Red was the original red cream soda.
I’ve had both Canfield’s and Dr. Pepper’s versions, and DP had the superior version by far.
I loved Slice when I was a kid but was never much of a soda drinker and cut out most everything except water/tea/coffee as an adult. I Googled and it looks like Slice now exists as a diet version exclusive to Walmart.
I heart Fresca, when I can find it. It’s like 50/50 (I believe that’s a Canfield’s product?) only sugar-free. My husband loves RC cola, which I don’t understand. It has even more of the weird coriander-ish flavor I can’t tolerate anymore in colas. I rather like Moxie, I loved a South American drink called Inca Kola…but that Malta Goya stuff can burn in in Hades. It is neither beer nor soda, but some unholy orgy of the two. It’s like the opposite of kvass, which can be rather tasty.
Off-topic, I miss Schweppes Bitter Orange, and wish there were more tonic-based pops. 
Edit: but the worst readily-available US soda has to be Mountain Dew. It coats your throat like store-brand cough syrup; not refreshing at all, just reminding you of all the corn syrup and artificial flavorings. I’ll swill nasty Diet Pepsi any day over Mountain Dew.