It also depends on areas in the UK. When we were looking to buy again in the UK. we were quickly outbidded on the first 3. One sold for £50,000 more than asking price. A relatvie recently sold a house in the netherlands within 3 days! Spain is different. To offer 40% less you need to have a knowledge of the property and it’s owners. Are they desperate to sell? How long has the house been on the market? Has it already been reduced?
I have friends in marbella who have had a property on sale for cerca 3 years. They were asking 975,000 euro and have gradually reduced it to 695,000. I think they may accept about 645,000 but wouldn’t consider ridiculous offers even though they are keen to sell. A property that has been on the market for some time is likely to have already been reduced a bit. Spanish sellers rarely reduce by much. In the 90’s we decided to put in an offer for a villa owned by a Spaniard. Offered 2 million pesetas less which was minimal. He came back with a 2M increase on the original price. 😮