This isn't even close to an accurate polling. You can't just ask people to post what they use and expect it to be even close to an accurate sampling of all chess.com users. Polls like this should be banned, because people believe it to be the truth, and it doesn't hold an ounce of scientific merit of an actual survey.
Now on to my post.
For some reason here it's considered "bad" or "looked down upon" to follow the rules and use books. It doesn't help when the "holier than thou" attitude of the circle of "trust" looks down at everybody following the rules. They say they don't, but you can see it in their comments.
That is by far the worst group at chess.com, not by the idea behind it, but by their actions.
To tell you the truth, I really don't like most of these people saying they wont use databases because they all sound like pompous people trying to toot their own horn.
I sometimes use game explorer for lines I want to learn, but never for more than 5 or 6 moves. About 50-60% of games I play without reference to any books or game explorer. This is not because I disagree with using books and databases - it's in the rules that you can use an openings database, so that's as much part of the game of correspondence chess as en passant or castling - it's because I'm here to learn and improve my chess and don't think I can do that by using databases all the time. I learn my favourite opening lines from books and try to use them in the same way as I would for OTB.
Anyway, if someone just blindly uses a database things will go off-line pretty quickly and if they didn't know what they were doing then they will lose in the middlegame.
I think using an engine is totally pointless - why bother playing if you aren't actually playing? I don't care too much if someone is using them against me, because their rating will reflect the engine's rating and I will probably improve by doing my best against the engine, win or lose. I don't own a chess engine and never intend to, because they bore me. I like playing humans, not silicon.