A Question on Baptism

As I stated in my previous post, I played for another church today. I sat in on Bible Class, as I played for both services and had to go somewhere in between. The class is studying parables and they wrapped up the parable of the Sower and moved on to the parable of the tares and wheat.
I found a couple of odd points in the discussion. The pastor asserted that the tares are the hypocrites, and the field is the church. I guess I always thought that the field is the world and the tares are unbelievers. Okay, I can live with this idea.
My question comes from the subsequent discussion. They were discussing hypocrites and the sacraments and the passage about eating and drinking to one's condemnation. Then the question turned to baptism. Someone asked if a hypocrite is baptized, is it a valid baptism? The point was made that this would have to be an adult convert in this hypothetical scenario. Both the pastor and the pastor emeritus said that they thought is would not be a valid baptism, and might possibly go so far to say that the person would need to be re-baptized when they turned from their hypocrisy to true faith.
Here is where I'd like to hear from you and/or your pastor. What do you think?
Are these two pastors correct? Is a hypocrite's baptism valid?