Twitter Icon
Go through Twitter’s trending lists to read tweets from random users, and notice how the ones with the generic Twitter bird avatar are generally just full of hashtag gibberish. More often, I run into it as the avatar representing spambot accounts. So I’ve come to associate this icon with something mildly unpleasant, sort of like the “missing image” icon in a web browser. If this is a logo mark Twitter wants to associate with the company, they should stop associating it with their worst users.