You could call it marketing or you could simply call it blatantly lying to the client. It is also deceiving many (generally first time) purchasers who are attracted by the low asking price, and them shell out £150 or so for a survey... at least now you can just check the land registry for similar properties in the area to get an idea of price and so you only have to pay a couple of quid for your ballpark valuation (this is pretty much what the surveryor does anyway to my knowledge)
the other factor in it is that the estate agent may also charge on a sliding scale.
0.5% for the offer price 1% for 5% over 1.5% for 10% over,when they know pretty much exactly what the market value of the property is and what it will sell for anyway.
this sort of practice just puts them in the effing scum category up here as far as I'm concerned.
cheers
David