1. Sending a text message with little or no expression that may suggest the end of the texting conversation. Such times when a vaguetext may be used is when you are texting someone uniteresting, you are busy at the moment, or you are simply tired of texting him/her.
2. A vaguetext may be used to test someone, and see if the person you are texting will reply with a new conversation starter. Such a case does not nessesarily mean you want to quit texting, just that you are opening the conversation up for a new topic.
Common examples include:
Jerry: Gawd I hate texting Britney!
Adam: I know, vaguetexting is her thing i guess.
Ryan: So i just got a new bike! :)
In the above example, Nick vaguetexted Ryan, implying that he was uninterested in him getting a new bike.