It happens all the time at the lower limits, so I'd guess you've done it a few times yourself.

If you're being honest with yourself, it might even be your standard play.

I don't blame you. Some poker theorists claim the chance to see a free river is a big reason for betting the flop.

I couldn't agree less.

What Does Checking Say About Your Hand?

When you're in position, you take the initiative on the flop and then you check the turn, you're basically telling your opponent exactly what you have.

This is the worst thing you can do in poker.

You're also not selling a story that you're particularly strong. If you have a strong pair or better, you'd bet to protect it - especially if the turn is a blank.

When you check your opponent can be 99% certain you're on some sort of draw and will know how to play against you later in the hand.

You Give up 4/5 of the Pots

When you take the passive route, you basically give up on 80% of the hands and only play for the remaining 20% - the times you hit your draw.

And every fifth time, when you hit your draw, your opponent can be quite sure what's going on and you'll have a hard time extracting any value.

You can call this a lose-lose situation.

What Will Happen on the River?

Let's assume your opponent is a competent player and understands what's going on. Then these scenarios are likely to happen:

The river is a blank and your opponent bets out on a bluff (he may also have been drawing). You'll have a hard time calling and you might not even beat the bluff if you do.

The river is a blank and your opponent has a semi-strong hand like second or third pair. He checks with the intention of calling if you bet out.

The river is a blank and your opponent bets out for value.

You hit your draw and your opponent check-folds. (An exception to this is when you have a double gutshot. This draw is less obvious than open-enders and flush draws and you might get called.)

More Semi-Bluffs on the Turn = Higher Win Rate

Since continuation betting is the standard play nowadays, betting on the flop says very little about a player's range.

In this situation, an opponent who sits with any pair is very likely to call.

On the turn, however, you will be able to chase away a large portion of the hands your opponent automatically calls with on the flop.

And there's a lot of value in taking that opportunity.

When you hit your draw, you'll be able to extract some value. Compared to checking, your range is now a lot wider and you might get your opponent to call with a semi-strong hand.

Betting the turn also makes you a lot tougher to play against.

People will think twice before calling you with questionable hands in the future - they know you have another bullet just waiting to be fired.

Further Reading:

The Most Repeated Lie in Poker

The Most Unfairly Maligned Move in Poker