Slippery slope reasoning is completely incompatible with 4th amendment interpretation, because the 4th amendment is all about what is "reasonable" (or rather, what is "unreasonable.") It's about compromising the legitimate needs of the police with the legitimate privacy interests of the people. You can't make compromises when your retort to everything becomes: "but if we keep going in this direction..."
This has worked against the government as often as it's worked for the government. And on the whole it has been instrumental in driving social change for the better.
The same Supreme Court that voted that equality could exist with "sepatate-but-equal" facilities later voted that separate-but-equal was not reasonable and full integration was required instead.
This drives "strict Constitutionalists" batty but I find it's one of the key benefits of our system of government.
There's no way to get a legal code that is both very exact and useful in the face of humans who have to implement it.
And even if we could, I don't think revising it every n years is good policy. We should change the law when it's broken, but more importantly changes to the law must necessarily lag several election cycles behind the needs and expectations of society. A court can actually make the change quicker if need be.
Sure, there needs to be a low pass filter of some kind to prevent wild oscillations in the law due to delayed feedback, but we're getting oscillations now in the form of party swapping every 4-8 years. There must be some way to make the law less like a moving average filter and more like an adaptive Kalman filter so it can react quickly when necessary without throwing out the entire USC every election (though I have, in the past, proposed rewriting the entire body of laws from scratch once per generation, with a generational opt-in-based transition from the old set to the new set). Courts should be a last measure, IMO, due to the insane costs of facing one, rather than an integral process of deciding what the law actually is.
If the officer witnesses someone break into the residence then sure, but just hearing something? That doesn't pass the smell test to me, regardless of whether it was about drugs or not.
What are the sounds of a house being burglarized anyway? The homeowner could just be moving stuff around in the living room when the cops bust down the door without knocking. That's property damage that the homeowner is likely stuck with and in some cases it ends badly with someone getting shot.
This whole no-knock attitude that's been in place for decades is a sad joke.