To caulk or not to caulk

[Sylvia B.]

When installing a tub with surround such as this one 

should one caulk the joint between the surround and the tub?

I've always seen it caulked, but a plumber told me that doing so is actually counterproductive and encourages mold growth. He said that the surround overlaps the tub flange, so caulk is not needed.

What say you?

[Rob Myers]

What does the manufacturer of the surround say about caulking?  I put in a replacement tub and surround about two years ago and the instructions were VERY specific on where to caulk versus where to leave room for water to drain out of the system.