I'm pretty sure *some* vendors look at the Zoopla estimate and take it as gospel when considering offers. We offered on a place a while back with a Zoopla estimate of £240k, and the EA suggested they wanted just that. Fast forward a couple of failed buyers, we put another offer in and this time (despite the broken chains and wasted time they'd suffered) the vendor now wanted the new Zoopla estimate of £247k! A month on I note the estimate has just dropped to £232k, I wonder if the new buyer will now gazunder?!