If you were viewing a property...

[Mummagumma]

....and each step you took made a sort of clunking, thunking noise (not the squeak of floor boards) what would you think it was and how would it make you feel about the flat/house?

I would think there was something wrong with it but wouldn't know what it was! Is this your house? What's making the noise? I'm intrigued

Am I wearing metal shoes?

Maybe no underlay if it was carpeted?

I would ask or make a comment.

Was it carpetted? Or wooden floors? Did it move or just clunk?

Is it the floorboards bumping on the pipes?

If it's the house that you're selling - get them fixed.

If it's the house you're buying - ask. Depending on what you're told, it might be fine. but unless you ask you don't know.

It is my flat, yes. I think it's a problem with the joists, and that it's really obvious and a real turn off to viewers. Ostrich-headed DP is refusing to believe that it's a problem, and does not want to get it fixed. We're currently arguing over email about it.

It will definitely put buyers off. Get someone in to at least have a look and give you a quote for a quick fix.

As missmehalia says - or if you don't get it done you could tell prospective purchasers it will cost x amount (if they ask)

We viewed a house where the floor upstairs seemed to be on a bit of a slope (10 yr old house). Surveyor DFIL said that it was due to the floor not having been put down properly during construction. Not a difficult job to fix but would have involved taking up all the boards and securing properly. It made us start looking at the rest of the house more closely which showed up a number of other issues which we hadn't originally noticed.

I'd say get it checked out and fix if easy/cheap if more complicated to show potential buyers (if they ask as missmehalia said) which does tend make a buyer think that you aren't trying to hide loads of defects.

sorry - that should have said as Starfish said