I tend to follow this approach as well. I tend to read posts and mark votes without noting whether they are anonymous or not -- by votes tend to be more fast-twitch than studied. (I actually use some CSS magic to keep my vote button floating in the upper left corner so I never have to scroll to look for it.)

That said, sometimes I upvote for quirky reasons not related to the quality of the response -- if someone phrased something particularly well or took a stand on something that might be risking some downvotes. In those cases, my upvotes tend to be more personal -- a shortcut to writing a kudos note in the chatterbox. I don't usually give those kinds of upvotes for AM posts.