except you all need to keep in mind what Pinkie's definition of "friend" is. She uses the term much much more casually then anyone else does, to her "Friend" isn't some person you are close to, it's "Anypony that is not openly antagonistic to me."
And yes there have been instances of characters being hostile to her, but the thing that separated them from Cranky was that Cranky was moving into Ponyville, not just visiting like Gilda, or not at all related to like the buffalo. Pinkie prides herself on the fact that every pony in ponyville is her "friend" by which she means "I know there name and they smile and say hi to me when I say hi to them"
Cranky was moving into Ponyville and so fell into the, "Is my friend becuase he lives in Ponyville" category, many other ponies may have just smiled, said thank you to Pinkie for welcoming them and just went on with there day, Cranky is the first on to actaully say "I don't want to be your friend", which is really the ONLY way Pinkie would not consider somepony to be her friend.
Yes some the desperation attempts get a little eye rolling, but the only one I really thought went to far and no way she shouldn't know better was blaring out that Cranky needed a wig to all of town, the rest felt very in character. And remeber she DID accept that Cranky just didn't want to be her friend, and she realized she had gone to far. Which is progress for her, at that point it shifted from "Must make him my friend" to "Must apologize for my screw up" She just failed to realize it was the exact same actions that got her in trouble in the first place.
Build a fool proof system, and the world will create a better fool.