Raising with an 8 or 9 out draw on the flop isn't bluffing, it's betting for value. You WANT action, especially calls. You have 32% - 36% equity (on the flop), so you'd like to play it out with multiple opponents.

Betting often (1) eliminates a couple of opponents, (2) earns you a free card on the turn, or both. Check/raising almost certainly accomplishes both.

The worst lines commit chips on the flop but don't see the river.