To be clear...and not confuse terms, there is a piston seal and a piston dust boot. If you were truly melting your piston seal, I would feel at the time of failure it would be a far bigger deal than a squishy pedal
Cracked and shitty looking dust boot is another story...this is pretty common. In fact the worst I've seen basically were 6 months new...cheap kits from local auto parts store. Shitty rubber I guess. But the piston seal was never and issue...in fact we got the brakes so hot the caliper forks embedded into the pad metal(25 hour Miata with sport brakes and more HP).
Only leaks I have seen are at the bleeder, brake line connection or the back of the piston where the e-brake mechanism is at(this seal can be damaged or forgotten when messing with e-brake disable).
If you are truly having piston seal failure(more than once)I'd be looking at your rebuild process
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