My wife and I have always tried to be respectful spectators, cheering on the players as appropriate, and keeping sideline commentary to a minimum. The one time I was tossed was because a very vocal father was behind me in the stands , and the ump thought it was me. Of course the other dad had a good laugh with me afterwards.
It always cracked me up all the sideline coaching. Really, your kid is going to swing the bat correctly now that you have gone into his/her ear (and his/her head).