I ignore OIEO too. Or, more usually, I completely ignore the house as it suggests that the owners aren't actually interested in sensible offers.
There's a house on my street that's been on the market for nearly 2 years now. They started at £265k (in a city where you can easily buy a nice 3 bed semi in a good area for £100k less than that) and subsequently reduced it to OIEO £249,950. I take it this means they've realised that no one is going to pay over the stamp duty threshold but haven't come to terms with the fact that they are only likely to get £225k for it. The problem is, they bought the house in late 2007. It's still on the market, but they never get any viewings (presumably because no one thinks they'll be willing to take a realistic offer).
Another house in the area has been on for at least a year at £270k. They've just put it on with yet another agent at OIEO £280k, which makes no sense at all. It's still listed at £270k with the other two agents. I doubt the new OIEO price is going to inspire anyone.
A new build one is on at OIEO £270k too and absolutely won't sell. The estate was built in 2006 and the current owners paid £270k in 2007. They obviously can't afford to/don't want to take a loss, but have been very unlucky to have bought when they did. Almost nothing on that estate sells and any 4 beds (like this one) tend to go in the region of £225-250k. The EAs still value them at £265-£325k regardless.