A phony Brony is the general Brony, with the exception that they don't truly watch the show for the love of it but more for the trolling they give from it, since there are many people who find the thought of grown men watching a little kids show really lame, some attention-seekers decide they will get in your face about how much they love the show and trying to start discussions about it with certain people knowing their reactions to the topic. Phony Bronys aren't really at all but more attention-craving trolls, you can easily tell if someone's a phony brony from when the topic comes up, a brony would say to someone whos hates them "oh well that's your choice." and talk to people who do like the show about the episodes, and phony would say "I love mlp! why do you have a problem with that! deal with it! we r changing masculinity!" and talk more about how "irritated" he is about brony haters to bronys rather then the show, also, the fan art they post on their blog about my little pony would rarely involve the shows ponies, and more or spin-off's of celebrities and well liked other shows (eg Brock Obama and Michelle Obama making a somewhat brook-hoofing hand shake) just to irritate people more by making them feel suffocated by the show by everything. Phony Bronys are probably one of the only reasons (besides cloppers) that people feel they have reason to dislike bronys.
Example 1: "Hey don't judge Jack for liking My little Pony Jack!"
"Dude, he doesn't really like the show, it's obvious he is a Phony Brony."
Example 2: Brad: Hey dont judge me, I love the show!
Timmy: Brad, I know your a Phony Brony, you never talk about the show unless in heated debate with someone who doesn't agree with you, get a life!