It's been almost a decade now, but a crew I used to hang out with in SF was very into using 'K' (as they called it) recreationally. The core of the group were aging, late 90's era ravers that had been taking molly very regularly for decades. Some of them used 'K' daily, often mixing it with adderall, which gave it a blue color that I thought was the color of ketamine for a long time.

One time I ended up at party with aging-raver-crew (in bernal heights iirc) that was also a polyamory meetup. One of the dudes there had a ketamine prescription and took a bigger dose than he was prescribed (he was a secondary partner to some woman that was significant in the effective altruism scene). I spent a lot of time talking to him and after he took the dose he said it was like he was "far away from everything and had to dig himself out to interact."

A few years later I learned that taking K regularly, and at high doses, can destroy the bladder irreversibly, and many people that get addicted end up peeing blood and having to wear diapers.