I have some experience over the past 35 yrs with many different instruments, and lots of times have been of the mind like Pippin, janeray and Dean above, but lately I am more open and patient to look for and find something special in a particular instrument, and most of the time I have an idea of what I am looking for, but other times I do not, and having more than a dozen ukes now allows me to play the one with the sound I want 'at that moment in time'. I doubt I would ever be happy with just one uke. This also plays into WHY I play, and it is mostly for myself and for my songwriting.
I've become more of a purist in my recording endeavors, and while you can EQ and fiddle with knobs to make things sound different, I prefer to start with something that sounds different 'in the air' or feels different in the hands, rather than molest the sound all fubar in the computer...and then capture, as accurately as possible that natural sound into the recording.
I dont much play in public or in groups, so that is not a big concern for me now, however in the future that may change depending upon the issues that arise when that happens...
However, lately I am more open and in agreement with acme and Bill as per below, and have often been rewarded with more patience by finding new things to enjoy in the sounds and playability.
...So if I like a uke enough to buy it, I do expect to spend some time working on our relationship.
I'd never make a blanket statement about buying a uke. Each buying experience is different.
That's not to say that if an instrument sounds bad to me, as soon as it's in my hands that I will keep it or buy it, for if it sounds dead, lacks resonance or has little sustain, likely I will pass, and I can tell right away and thus will not waste more time on the instrument since we have such a wide plethora of choices. We truly have an embarrassment of riches with all the different makes and models available to us, from worldwide vendors and makers now, so it makes no sense to buy or keep something that is 'less than'.
Further it does take some experience to KNOW an instrument that is 'less than' another, which most newbies lack completely, and later on this plants the seeds for UAS...