In reply to Fränk Klein.

It's not impossible to create some guidelines around good coding practices and using WordPress standards. Those are not generally plugin specific though. You're probably taking what I said out of context, which was meant to be a comparison with how theme guidelines are done. With themes, there's an extremely strict set of things that all themes must follow. You must have a style.css. You must have an index.php. You must use this function to show posts (and you must show posts). In general, all themes are going to be very much alike. That's just not the case with plugins.