Edit: Thanks Guv for separating the thread, it was clogging Adrian's thread up... (sorry Adrian!)
Thanks for your reply Simon. To clarify, my flux was bought from you, not GJH, my cleaning regimen is daily and thorough using Barkeeper's Friend, though I've also used Viakal, and always well scrubbed with a toothbrush. I don't slosh flux on as I have a CPL flux pen which unless over-squeezed, which happens from time to time, is very accurate in its placement. Nevertheless a blue/green sticky residue often appeared after use - sometimes days, sometimes weeks - and it's something that has never happened with Carrs Yellow.
However, that's only half the reason for my discontinuation of its use - the other is that the fumes irritated and even hurt my lungs. I don't solder in an enclosed area, I have a solder fume extractor in constant use which receives a regular change of filter and an extractor fan to fresh air which is usually on. If required there is also a window within reach and a door opening to fresh air too. In addition to the extractor and fan I always have to open the window and door when using safety flux (uncomfortable in winter) and only the former two with Yellow. I don't have any asthmatic or other respiratory tract issues.
I know that lots of people use your flux with no problems whatsoever, I've seen some very clean soldering work done with it both in the flesh and online, and I've read some glowing testimonials - in fact at one time I thought that I was the only person to experience any problems with it, but I now know that isn't the case.
I really don't believe there is a panacea for flux, just as there isn't one for a post-soldering session cleaning agent, or a soldering iron, or an airbrush, a make of paint, a soldering iron, a file... sometimes you have to try a number of alternatives to find the one which works best for you.