Wouldn't bother me in the slightest. For instance my Mum's mare failed on a flexion test one week and passed the following week. Depends on the day I think.
Would depend by what margin they failed, what I wanted to do with them, how old they were and whether I wanted to insure the horse. But yes if Flexion failed would want to negotiate a discount.
It really depends, Flexion tests can give different results with different vets. One vet I used years ago told me you can make any horse lame doing a flexion test. It all depends how much and long you flex. Its a bit like you sitting in an akward position for a while, you are usually stiff for the first few steps you take and then fine. A horse is quite the same. If you're not sure I would get an X-ray done.
I'd seek my vets advice but it wouldn't worry me.
My pony failed her flexion tests aged 12 when vetted but we still bought her and she remained sound for a good 10yrs and is now retired mainly because I've out grown her.
On the other hand my horse flexion tests sound on his two lame legs, so funnily enough I don'tr trust them at all.
Flexion tests aren't infallible and as daphneb says you can make a horse fail by holding the leg higher / longer. If you're that worried by a flexion result why are you not having a complete vetting?
I said yes, but I guess it would depend on how badly the horse failed. If it was hopping lame I wouldnt buy.
I did buy the chestnut in my siggy after she failed on the flexion test. She just trotted a few paces a bit short and then went sound. But to be honest I was so in love with her it really wouldnt have mattered what the vetting showed, I was going to have her