A bad trip can absolutely happen on LSD. I wouldn't say it's about "taking too much", moreso bad set/setting...I mean, yes, some people simply can't handle the more extreme side of the psychedelic spectrum, so they'll freak out on a high dose, and if you weren't expecting a trip to be super strong, then it is, I can see how that would throw you off. Personally though, I think where bad trips are most likely to happen is at a dose that's high enough that you start to lose control...but low enough that you still want to control it. This dosage range can still offer many wonderful trips, but when I've had difficult trips (only one of which was with LSD), they haven't been the real heavy doses, they've been in this range (which is unfortunately the highest most are willing to go, as they are unwilling to really surrender to a trip).
On a truly heavy dose, I no longer desire control, and I'm 100% immersed in the trip, so while I may get anxiety in the come-up, ie the transition between "normal" and heavy tripping, once I peak it's golden (for the most part), and these heavy doses are where the real life changing trips, ego-deaths, and other profound, mystical trips really come into play. I will say though, that such heavy trips are not something to do every time I trip, they need to be reserved for when the time is right, and they truly are quite an endeavor which you need to be prepared for much more than a normal trip.
As for the terminology of "bad trip", I do think of a bad trip as a learning experience, but that doesn't stop it from being a "bad trip"...if it's uncomfortable for most of the trip, that's bad. I can gain some useful knowledge out of it, but I'm not gonna pretend it didn't suck to be there afterwards. However, I don't go out of my way to avoid bad trips like many do- I do make sure my set/setting are good, but fear of a bad trip seems to stop a lot of people from letting themselves have a truly profound trip of any sort, I'm not about "playing it safe" (except for physically, though I'll admit I've done some straight up stupid shit in the past), to an extent I definitely believe that "if you don't at some point think you've taken too much, you didn't take enough"- however, if your a psychedelic newbie, then you actually should play it safe until you've tripped enough times to have a good sense of how well you handle it, most don't handle it as well as me & other high dosers! You've gotta be very grounded and able to maintain some sliver of connection to normal reality/not lose your shit if your gonna go dosing high.