Dave:
Short answer: yes, I believe I do have a straight stroke.
Long answer: when away from an actual pool table, I practice with my
LaserStroke (yes, I have one of those -- but I'm happy to have one!). I don't do the "marking a dot on the wall" thing as recommended in the user guide; rather, I just aim at a paper Calendar across the room, and line-up / stroke the vertical laser line on top of one of the vertical lines (vertical date delimiters) in the paper calendar's crosshatch pattern, all the way through follow-through. I've been doing this for a couple years, and I think I have a straight stroke, even at the table (which I verified by actually using the LaserStroke at the table).
Also, I tried shooting shots with a stand-up dressing mirror positioned at the other side of the table, and as far as I can tell, my stroke is straight when shooting through shots. I had a couple folks look down my cue as I'm shooting (even when I wasn't aware they were watching), and they tell me the same -- no hooks/crooks in my stroke, a straight follow-through all the way until the forward motion of the cue stops.
Many folks don't realize it, but the grip plays a crucial role in whether your stroke is straight or not. Since your fingers wrap and underneath the cue, the top part of your palm (the part closest to where your fingers join your hand) and heel of your hand can steer the cue during follow-through. I know I had a problem for a very long time with the heel of my hand "bumping" into the cue (I'm a righthander), and since the heel of my grip hand is on the outward-facing side of my cue, it sent the butt of my cue ever so slightly to my left (towards my body), which diverts the tip to my right. I use a technique of curling my pinky inwards, like a little "ball" that rests on the outside of the cue, which pulls the heel of my hand out of the way. It's like a "space governor" that keeps the heel of my hand out of the way of a free-flowing stroke. It works for me, and keeps my stroke straight.
When I see you at SBE in a couple weeks, you can tell me if this is true, or if I'm out on Pluto or something.
Hope this is helpful!
-Sean