Golf clubs....cleaning irons?

In a word......yes. There is a reason Tour pro's have caddies ( not just to carry that huge bag lol) Consistency is the key to golf and anything you can do to aid in that will help your game.

Think of it this way, if you go 4 wheeling and leave dirt inside your rims then it's a fur shure you'll have wobble in the tires on road and highway use due to the fact they're no longer in balance. Same applies for your clubs if you leave the dirt in the grooves and the dirt against the ball can cause erratic flight just as badly as a smiley face on the ball.

Yes, every little bit of groove space there helps. I clean mine after every round, and yes REALLY clean them out....with a wire brush and hot soapy water

It helps to put more spin on the ball.

only if you use alot of spin on your shots, for a hacker like me no difference at all......