My biggest gaming disappointment ever was when I played Mike Tyson's Punch-Out on the NES for the first time in 1987. I had gotten fairly good at Punch-Out in '84 when I was 9 years old and it was my favorite video game until Super Punch-Out came to town in '87.
When my friend from school, Ryan, said he got "Mike Tyson's Punch-Out" for the vaunted NES, and invited me over to try it out, I was excited as the day is long. I was expecting it to be perfect, because I'd played Excitebike on the NES and it was exactly like the arcade version, aside from some minor details. I didn't realize at the time that arcade Excitebike was just an NES in disguise. I just figured that if they could do one arcade game perfectly on the NES, they could do any arcade game perfectly.
Instead of the perfection I envisioned while walking to Ryan's house after school, I got bad graphics, simplified sound (no announcer), bad animation (many of the movements are just 1 frame of animation, such as the dodge animation; and ironically, "stiff" is the way I've always described the MTPO controls), a ridiculous pull-down-to-block-up scheme, an equally ridiculous hold-up-to-punch-high scheme, an asinine hearts/stars scheme, and an absurd multi-round-have-to-knock-the-opponent-down-up-to-seven-times-before-he-stays-down scheme. Additionally, there are unskippable intermissions, your playable character is a 2' 6", 25 lb. Ultra Midget, and the opponents are 100% patterned, which is why it's possible to beat the game blindfolded.
I've never seen anyone lose to Glass Joe. I beat him, and Piston Hurricane, the first time I ever played the game when I was 9 years old. If you do nothing but constantly tap one of the punch buttons (with your guard down for "body blows"), you'll beat Glass Joe without him even landing a punch. You'll beat Piston Hurricane that way too, though he may land some punches. Bald Bull is the first opponent who requires any sort of technique to beat.