To distinct people that are using Steam as Steambook is quite easy: Their "steam rating" equivalent to be 0-1, whilst normal users has rating of 8-10. However, some individuals delude themselves and "pretending" to play game via "steam in-game layout" while game just running on a background; increasing your rating. Thus, for people to not condemn them in Steambooking.
17:42 - Steam user: Wanna play tf2?
17:42 - Steambook user: Sure, give me a sec
Steam user is now playing Team Fortress 2. Click here to join.
17:55 - Steam user: Are you coming?
Steambook user is now Away.
18:00 - Steambook user: So where we left? Sorry, just some normal steam user wanted to play with me; got on my nerve. I'll be "away" for now.
18:02 - Steambook user #2: So, how's life and family? Brother still bullying you?