It almost seems philosophical to discuss whether or not taking a bet they offer is abuse, even if you'd be certain you're going to win.
It's acceptable to VOID certain types of bets:
1. Late betting = Somebody has a better feed than the sportsbook, and they can see the next basket/goal before the sportsbook.
2. Obvious pricing errors = Detroit Pistons 58.8 instead of 5.8 etc
3. Matchfixing = abnormal and suspicious betting activity(Chinese Esports game gets 100x volume out of nowhere).
*Although some sportsbooks pay "late betters".