I could wear out my keyboard naming studios or producers I don't like, but I think mainly down to the genres they represent as opposed to anything else. Men@Play, Titan Men, Missionaryboys..... each have their own main selling point, and if you don't connect with that then you're never going to like their output.
I will concede that some studios just fall flat despite perhaps ticking all the right boxes on paper. Helix, for example, used to be one of my "go to" studios back in its heyday, but over the last couple of years they've stopped making entertaining porn with at least a hint of story and seduction and chopped it back to a very formulaic format.
FratX is one of the more annoying studios for me, mainly because it's become too chaotic. It's always been choppy camerawork and editing, and that is certainly an intended MSP, but it's degraded to the point that there's no sense of continuity. By the time you realise who's fucking who, or even which way up the camera is, the shot has moved onto something else. It's become a lot noisier too. Sketchysex follows the same formula, but seems to pull it off better, though I don't doubt they both fall under the umbrella of the same producers. I suspect Face Down Ass Up and SlamRush might be related to them too. I wouldn't say I despise any of them, and occasionally I find a real gem in amongst the rubbish so I grab new stuff when it appears.
I long time ago somebody asked the same question about performers. I remember suggesting Joey Mills for being wooden in all the wrong ways, as well as Denis Reed who I would want to see watch if someone described him to me, but after seeing him on-screen ruins every scene he's in for me, and I don't know why. There's nothing wrong with him, but I can't stand him.
I tend to steer clear of Himeros too. Most of it is a little bit too tantric for me, and so many of their films have a cast without anyone I fancy in them.For me to grab one of them I need to see a particularly special screenshot that resonates at that precise moment or see someone I really like in the cast list. I admit I've grabbed stuff I know I'm going to hate 99% of simply because of a well-timed pic that makes me want to see that few seconds of video.
I've got a huge library of films, but so many of them I've only kept for a small portion of the overall movie. I keep saying to myself that I need to go through and trim the files, getting rid of the scenes I don't like, and in some cases simply keeping a short clip of one cumshot out of a 2-hour film.