I suppose musically I'm a lumper as I find my favourite jazz & blues record shop (Ray's in London) overcategorizes everything to my frustration when I'm trying to decide where they'd put things. Their blues section has "honkers and wailers", for example, and the LP section "rare as hen's teeth" (with prices to match!). On the other hand, a delight to browse for the unexpected, only annoying when looking for something specific. I suspect it is the same with performing. If you are advertised as an Irish or Bluegrass etc evening people come to hear that. If you are less specific "song circle" etc then there is the pleasure of serendipity. Not that my opinion on anything folkie is worth a gnat's gonads.
RtS