Curious - what sucks about Sno-Seal?

I've used it for years and years on my boots, I apply it with a toothbrush and a hair drier to melt it and rub it into all the seams well and the boots have never leaked walking in wet snow for an entire season or even being dunked in creeks walking through them.

Obviously you had a different experience and I was wondering if you would elucidate a bit as just saying that it "sucks" doesn't educate us much. What sucks about it - applying it, longevity, water proofness?

TIA


Gunnery, gunnery, gunnery.
Hit the target, all else is twaddle!