It's not the pads, it's using the wrong pads for your setup's working temp ranges.
Know your setup, know what to buy
Various ways of doing this, from thermo-graphic heat paints to stickers. e.g:
http://www.demon-tweeks.co.uk/karting/pyrometers-temperature-indicators/a-p-racing-temperature-indication-strips
I am not sure this is true. My 4-2s were fine on the road, didn't notice anything. Then I went to Mallory Park for a trackday, I had to basically sack off the day because of horrendous pad build up. I cannot explain how horrible it was.... Eventually it went away after a few thousand miles of road driving (for the most parts) and at around 1/2 pad life they started behaving themselves (as Rich has found).
I drive my car exactly the same way, with the PMUs that I have now as I did with the Pagids (in terms of daily driving pootling around and the odd B-road blast and trackday) and yet I've not had a SINGLE PROBLEM with the PMUs in terms of pad build up, vibration, or anything like that, but the Pagids 4-2s were crap. Yet the PMUs have a higher maximum temperature range. So logic tells us that the PMUs would have issues with cold / daily driving type use... which they don't.
Online we see a lot of reports of build up / vibration with Pagid RS4-2s as well. I don't care what anyone says, the brake set up is brilliant. The Pagid 4-2 pads are sh*t and I'm glad Alex is phasing them out.
I don't understand your reply. The 4-2s were OK on the road because you didn't burst their operating range, you did a track day, took them past their range and they promptly sh*t their resin all over your discs. The resin you should have all burnt out if you'd bedded them properly in the first place. I did the same, I'm not being a tit with you.
They have a very fussing bedding procedure, in that respect they're a pain in the arse, but if followed correctly and used in the right application of car & brakes, they're fine. The chap from AKS has clearly done it right and manages his brakes accordingly to suit.... by braking properly, which most of us don't.
Now, I'd imagine if he took them beyond their capability, they'd simply fade - as there's no resin left to piss out. Yours no doubt would have been the same now you'd got the resin out of yours, albeit the hard way.
Sounds like they glaze a little from light use, that's typical of some pads and a quick kicking usually sorts that out and cleans the muck.
I still maintain they're not really suitable for the car's weight, but you could work around it. The main problem here is user error.
You also can't compare the hot/cold performance of an entirely different pad IMO.