I'm just a moderator, I don't have all that much insight into the inner workings at Bethesda and can't really speak for them or their practices. I do know that Gstaff and Jfinst at least keep an eye on the forums and I wouldn't be surprised if others lurk on here from time to time even if they don't post terribly frequently.
As far as the whole "shill" thing goes (paying people to post positively on the forums) that's one of those things where if Bethesda was doing that, there's no reason that I'd be privy to the practice. It would seem pretty silly to me, though - this forum represents such a small and specific cross-section of the fanbase that I can't imagine it being worth the effort. We do get crabby members on occasion that like to assume anyone who disagrees with them is a payed plant, but in my time on this forum I've never seen any evidence of this actually being a thing they do.
As far as listening to the fans, I think that's far more complicated than it might seem on paper, personally. There have been DLC and other additions that are clearly the result of fan request, and certainly if nothing else they're keeping tabs on mods. People also like to exaggerate the popularity of the requests they favor - it's always something "everyone" wants when it's a feature you care about, it seems. Plus, look at any thread on this forum - for everyone who wants something included in the game, there's another who steadfastly does not want that thing in the game. So... no matter what Bethesda does, they're going to be "not listening" to someone.
And forums being what they are, I think we tend to lose sight of the fact that these are people with their own ideas about the game they like. Not everything is going to be about "well, this idea was popular this idea wasn't." Not every single time a feature gets put in a game when there was a mod like that in a previous title means it was entirely a marketing choice. Around here we tend to lose sight that maybe some of these devs saw a mod and just liked that idea - I doubt it's always about what is or is not popular.
I can't imagine a development team not being full of people who also have very clear ideas of their own about what they'd like to see in these games and I'd be very surprised if there weren't constant heated debates internally about a lot of the same ideas talked about on here, too. (I'm sure there's been at least one argument over there about spears in the Elder Scrolls games, for instance. )
One thing I do recall from various interviews with some of the lead developers over the years is how they try to "read between the lines" when taking a barometer of popular opinion. Trying to look beyond just plopping in every feature that's ever requested on here, and instead trying to look past the surface details to really get at what people are really asking for, if that makes any sense (it's been a long work day...)