twowheels, yes that does seem an odd exclusion.
patrickt, I am guessing that genre "stacking" probably happens (perhaps using it as a tag system rather than a categorisation), but sometimes it is simply that the story doesn't slot neatly into just one category. I'm in the process of publishing some short stories that are proving very difficult categorise. So it can be appropriate to place a story in multiple genres.
The intention is, obviously, to try and be visible to all readers that might be interested in the story. Assuming this works, any readers lost due to preferences like your own
might be a cost, a trade-off, but I think it would be very difficult to measure the detrimental effect. (A lot of avid readers read widely, so showing up in all
relevant genres might be helpful.)
But a more relevant question might be: isn't what you describe actually a good thing for readers? Isn't it better for the reader to know in advance that the story might fit into genres they don't like? It may also be better for the writer to have turned away readers that are predisposed not to like the story, and so avoid predictably bad reviews.
Mind you, there can be some odd ones. I added tags to my novels and one of the tag words I chose (because it's significant in the story) is found mainly in non-fiction spiritual/mystic-healing genres. My (fantasy) book might look a little out of place in a search against that tag (although some might argue that it fits right in
).