@Vastness Indeed I am not completely sure and don't want to fuel myths but there is certainly more going on than tolerance. We had this discussion about MXE when many kept complaining the newer batches were bad and with time people agreed to that it was tolerance but as tolerance to dissociatives is mainly an almost one-way road, it shouldn't be the case to find a years-old baggie hidden somewhere containing a bit of original MXE and bringing that opiatey glow again when the newer batches were actually more potent sometimes but cold and pretty different. Thinking about it, isomers are indeed a possibility if the metabolite(s) mediating this glow are stereoselective like some opioids are (levo -> opioid, dextro -> nmda antagonist). Didn't read yet that this applies to arylcyclohexylamines like bromadol though and MXE is more of a serotonergic than an opioid.
With K it's difficult. My rational mind tells me it must be the isomers but as said even lab analysis isn't always accurate when it comes to unknown, close variants. There is the cold, clinical stuff. Trippy stuff. Euphoric, stimulating one. Some cause different optics than others which do almost none. Others are more anesthetically feeling. Have to admit that I don't have analysis of most of them but at least from potency, taste, consistency they all were pretty similar (either shards or powder- this can be anything of course but the possible RCs are different enough).
When reading that people fake K consisting of caffeine, paracetamol etc. then I have to be very skeptical though. Would love to sample pharmaceutical K and R-/S but guess this won't happen anytime soon :/
Biological factors are relevant for sure, with dissociatives maybe more so than setting.
Had similar experiences with some RCs btw, there is a definite set of 'modes' as discussed in another thread where each and every arylcyclohexylamine has different ones and while it appears to be pretty random which one you get (this is dependent on subconsciousness maybe? In pre-holes I tend to hover over structures which are based on the impressions of the past 6-8h) - they are definitive chemical, and now the point, batch related. DCK should always be DCK, etc. but there are different variants of DCK, and of 3-MeO-PCE too. They even have different durations, but same potency. DCK exists in a much more psychedelic and kinda MDMA-like variant, and in a heavily stoning one. Unfortunately again, no test but I wouldn't say that it's about cuts, I would have noticed the different quality of effects and stim rebound etc. It's all typical dissociatives.
I don't know whether gray area labs bother with isomers, and whether different synth routes will create differing ratios between isomers. Know too little about chemistry yet.
Correct me when I'm wrong!