I am mostly straight, and mostly indifferent to blowjobs. I’ve only had one that really did it for me, and it was more about the person doing it than the act itself.
I love them and I have had many and I cannot remember a bad one. Possibly the girls/women giving them detected how much I was enjoying them and joined in the enthusiasm.
I’ve gotten a couple in the long-ago past that were less than inspired. There’s more to BJ’s then just vigerous head bobbing.
But even a poorly done blow-job is still a blow-job.
OHH fuck … Dude I’m really sorry but i busted a freakin gut reading your post…
While mostly gay, I have had BJs from women. They really put effort in them, but they weren’t to the standard of those that a man gives to another man. Still, I don’t think they were bad. The worst BJ I’ve had was actually from another gay man. He was enthousiastic about it, but for some reason he didn’t know where the good spots were, and I couldn’t get him to understand.
I wish I could give myself head though. I’ve been told my BJs are the best anyone has ever had.
I voted “No such thing as a bad BJ,” as I’ve never had a bad one. (Though I do believe it’s possible to get a bad one – biting, for example – I suppose I’ve been relatively lucky.)
It’s true that I’ve had some that were, shall we say, less enthusiastic than others. But “bad”? Never.
First off, I’m with somebody I’m attracted to (and let’s face it, it wouldn’t be happening if I wasn’t), and she willingly takes my dick into her mouth. That, in and of itself, is a gigantic turn-on.
So every BJ starts out as “good.” It can stay “good,” or it can sometimes go from there to “great,” “outstanding,” or “mind-blowing,” but it would take a whole lot to devolve into “bad.”
I have to say I’m surprised at the number of guys who say a BJ can’t get them off. I love BJ’s. I love 'em so much that I sometimes have a hard time not getting off too quickly.
And, I’m very fortunate that the only woman I’ve been with for the past 16 years still loves to give them. 
I hate hate hate getting them from girls with tongue rings. They always pinch.
My best guess is that the declining prevalence of tonsillectomies in recent years has resulted in a sorry state of affairs. As it were. 
I had a girlfriend a long ways back who just didn’t get the concept of a blowjob. She enjoyed doing it for me, at least in concept, but she’d basically put it in her mouth and do pretty much nothing. Perhaps she was running her tongue around in there or something, but I couldn’t feel it. I gently tried making suggestions, all for nothing.
Thank goodness she was great in the sack in other ways, but oral was just beyond her.
In hindsight, I laugh too. She was terrible on so many levels, not just sexual ones.
I like to think my traumatic relationship experience is good - as a teaching tool.
The more you know!