I was a Spiritualist for 4 or 5 years, and there was certainly plenty of cold reading going on. For instance, the medium would very commonly say something like "I'm getting the name George here" with no further details; George could be somebody's husband, somebody's grandad, or somebody's budgie. But someone in the audience could usually identify the name as familiar to them; if they didn't, the medium would hurriedly say "Or it could be Gregory!" or something, until somebody put their hand up. The medium would then take a good look at them, then say something that might be relevant; an elderly woman wearing black would get "He says to tell you he didn't suffer", for instance (which could equally well apply to her budgie, I suppose).
I didn't start out sceptical; like the X-Files character, I wanted to believe. I actually wanted info about an important piece of family history that only a medium could supply; no medium I ever encountered (and I must have gone to at least one Spiritualist service every week) ever came near to telling me anything about it. Instead I witnessed performance after performance of cold reading, plus 'warm' readings from mediums who clearly already knew their sitters' backgrounds - greeting sitters by their first name and chatting about previous readings. Never once did I witness anything that convinced me.
Too, much of the 'evidence' for mediumship seemed utterly pointless - recitals of names, extremely approximate guesses at causes of death ("I'm getting a pain in my chest here" - so would that be a heart attack, impalement or just acute indigestion?), assurances that "he didn't suffer", rosy descriptions of the afterlife. I once had a session with Carol Polge, a 'psychic artist', who produced a pencil portrait of a young woman who looked vaguely like me; this was apparently some discarnate spirit she could 'see' with me. Carol didn't give me any messages, was unable to supply a name for this person and suggested I looked in old family photos for anyone who looked like her! I was too polite to ask her what it was all supposed to prove.
One mediumship group that I attended in the early 70's did seem to be more promising; they were channelling messages from a similar group on 'the other side' who were developing plans for a machine that could transmit 2-way voice communications between this world and the next. But nothing came of it - they were perpetually on the edge of the big breakthrough, but just faffed around; eventually I left and never heard anything more of it (I know this sounds a bit like Raudive communications, but this group were already familiar with Raudive's work and were adamant that their concept was entirely different).