It can be forgiven if someone links from a REAL site that doesn't allow image linking (for example, if you try to link from SomethingAwful.com). But when it comes to sites that even your 4-year-old cousin knows don't allow it, it's just fucking stupid and annoying.
Hay Dumb fuck, don't you know that image leaching makes you gay? If you want to post images get your own webspace and host them yourself.