I've used both Stylast treatment and their stylus cleaner without problems. With the stylus treatment, one should take care to only apply a very small amount directly to the stylus and avoid slathering it all over the cantilever. The fluid dries to a sticky consistency and some people have had issues with that goop getting up into the cartridge's suspension. There are some claims that liquids applied to the stylus and cantilever can migrate up the cantilever by capillary action (wicking).
With liquid solvents, always leave some amount of time between cleaning and playing the record to allow the glue that holds the stylus in place some time to harden (in case the solvent softens the glue). Lyra makes its own liquid cleaner (so it is presumably safe for their cartridges), and they recommend something like a 10 second wait between cleaning and playing to allow the glue to harden.
I have not used Zerodust, or any other such sticky pads to clean my cartridges. My concern is with accidentally pulling the cantilever out of the suspension. The suspension is design to accept the load of the tracking force pushing in one direction, but not necessarily the force pulling in the opposite direction. I know of someone who pulled the cantilever of his Allaerte cartridge out of the body of the cartridge using one of these things. I don't know if this is something particular to the Allaerte, or whether the cartridge was somehow damaged before such use, but, in any case, this was a VERY expensive attempt at cleaning the stylus.