dietary profiling - the new sexism?

i noticed quite a few available apartments on craigslist for which a vegan/vegetarian applicant was preferred. i guess that's not terrible because i also saw postings where a sex was preferred. some guys do not like living with girls, and vice versa.
it seems a little unethical to consider someone first because of their eating habits. i understand if someone with a cat is put lower on the list because the current tenant has a feline allergy. or perhaps you want someone who regularly exercises because you have a nice bathtub and don't want to relive the President Taft incident.
i have never heard of anyone being allergic to meat, and if this exists i would love to read some documented cases while lightly chuckling over a perfectly seared hunk of flesh.