Re-negotiating the price...

Having chosen a property to buy you will take in to account all relevant factors including its asking price and how close it is to satisfying your criteria when formulating an offer.
Negotiations then would usually take place and you finally agree on a price known as 'the sale price.'
Once the survey is performed you may have reason to try and re-negotiate the price.
We sometimes have buyers coming back to us saying that as the survey says the window frames are rotten they want a £5000 reduction in the price. Our answer would be short and to the point. "Sir/Madam, when you made your offer you were well aware of the fact that the window frames were falling out and therefore it is very unlikely that our vendor will agree to a price reduction."
If, however, the survey identifies substantive problems of which you could not have been aware, then this is a different matter. For instance, if the survey identifies that the drains are leaking badly and need immediate replacement then it is only fair that the seller should agree to at least share the cost of this work; perhaps on a 50-50 basis.
As with all things these matters can usually be settled amicably, providing both sides are flexible and act in a reasonable fashion.