That most fans hate this episode and/or Bela is such a granted aspect that the writers' later made it text of the show that this was a bad episode and Bela wasn't a good character. (This opinion becomes canon in season 5). I will grant that Bela episodes, this especially, do have a much different tone than most of the series. The writers never did know quite what to do with her outside of being a vague foil for Dean. As a result the Bela story ends up being ultimately fairly lame. Fortunately, the first couple of episodes with her are not all that serious and I love the character as a comedic foil for Dean. It is also true the plotting in this episode is quite contrived.
At its core this episode is a screwball comedy. It has all the classic elements of sexual frustration coming out as banter, battle of the sexes, high society etc. It even manages to work in some deconstruction by having Dean acknowledge Bela's objectification of him. It is all delightful to me and funny. The humor is old fashioned-yes it is ultimately misplaced in the overall narrative-but it works well enough here to be hella entertaining.
The ghost story, as well as the clues to Bela's past, is quite engaging. And apart from anything else this episode has some of the finest visual effects and atmospherics on any other on the show.
This is one of my favorite episodes even if yes I get why it is disliked so much.