If we're still talking about horizontal skew, it's something that you want to try to take advantage of if you believe that it's going to change. On its own, I'm not sure that it's an indicator of anything.
ok, but surely you would need some kind of screen for at least getting a list of possible candidates, right?
Not necessarily. One way of trading is coming up with some generic criteria and then searching for candidates that fit the criteria. The other way is that you already have a stock (i.e. follow only a limited list of stocks) and you are just looking for the best option strategy to implement on this stock given your forecast and current option pricing.
Over the years there's been chatter here from peeps looking for a web site that offered skew screening. As far as I know, the general consensus was that it was only available from a data service (subscription fee). When I actively traded them, I'd DL the weekly McMillan IV numbers and correlate them with the upcoming 1-2 weeks of expected earnings announcements. If the 1 week ROC in IV showed no bump week to week, it was discarded. If it did, then I checked out the option chain for possibilities. It's a lot of work but finding good set ups always is.