I think you've hit the nail on the head there. No one wants glory hunters taking up loyal fans' tickets, but the assumption that all blues with non-Manc accents fall into that category is just wrong.
Growing up in Bedfordshire and having to support City (Dad didn't exactly give me a choice!) wasn't easy - Utd and Liverpool fans everywhere - and my brother and I got plenty of abuse. Then when we started to get good we got the whole 'glory hunter' jibe thrown at us, which annoyed me so much that I started carrying a pic of me from 1986 at three years old wearing a City shirt! Now, having fended all that off, the thought of fellow blues might give us stick for our accents makes my heart sink a little.
I must say, I have noticed that our nob-head quota seems to have increased a lot these past few years; or, perhaps, they've just become more vocal. Because of where I live I used to go to about 10-15 away games per season, maybe 3-5 home games, and never saw any blue-on-blue trouble. Previous two seasons I saw it at every away game, as well as every trip to Wembley (the worst being Community Shield just gone). And for those playing at home, the answer is b) Cocaine...