Glad you guys approve! Here are a bunch more:
10) Romance Obsession. This is ignoring all other aspects of a roleplay in order to fulfill romantic fantasies. While focusing on mostly romance in a romance-focus roleplay makes sense, doing so in a more general roleplay can be detrimental. For one, a romance can usually only occur between two people. This means that a player with Romance Obsession will focus all of their character's attention on the object of their romantic attraction, and ignore every other character, to the roleplay's detriment. It is also unreaslistic, as most people are concerned about things besides romance, especially during zombie apocalypses and supernatural wars, which are common in roleplays. Why is this character doing nothing but pining after a boy when her life is in danger?
11) Instant Romance. A combination of Romance Obsession and Illogical Events and Behavior. This is when a player is so eager for romance, they have their own character fall in love with another character for no other reason than that the player finds the object of their character's affection to be attractive. While this can make sense if the character falling in instant love is portrayed as shallow, often the player wants this to be true love. Instant Romance ruins a chance for interesting and realistic development between characters.
12) Illogical Events and Behavior. This covers just about anything in a roleplay that makes no or little sense. Instant Romance, as described above is an example of this. Characters should be consistent, and NPCs should act in a logical manner.
13) NPC Puffery. Using Non-Player Characters in order to make one's own character look good. For instance, a player might have their character make a painting, and write that everyone in the class gasped at how beautiful it was and that the art teacher declared the piece to be a work of genius. Someone playing a wolf may say that a rival pack attacked and all were beaten by their own character. This is a form of Mary Sueism, where the world around the character is manipulated in order to make the Sue look cool by comparison.
14) Leaving People Behind. This is especially relevant in forum roleplays, where response time is expected to be slower. While it is unreasonable to wait forever for someone to post, it is also unreasonable to post so quickly and often that they are left behind. When the fast posters' characters are alone together and their actions do not effect anyone else, not waiting for others makes sense. However, it is different when everyone else in the roleplay comes back after a few hours to see seven pages of just Fast Poster 1 and Fast Poster 2, who have jumped time forward to the next day.