LilliFoster:

Geez - I like his "syrupy" vocal.  I thought it was "smooth."

"Syrupy" isn't the term that I would have used. Mumbly,  maybe hoarse? I personally stopped listening to the Doobie Brothers when he "took over" the vocals. Everyone has their own opinion though which is great. Actually there are a lot of bands that I listened to in the mid to late 80's that I'm almost ashamed to admit listening to! If you liked him good. He did write some great songs I just didn't care for his singing.