[dznutz]

That's not so hard now, is it?

You forgot #6. Bad guy sees cops at door and flushes contraband and down toilet while police wait outside.

[DuncanWaring]

You forgot #6. Bad guy sees cops at door and flushes contraband and down toilet while police wait outside.

And nobody gets shot.

[ExGeeEye]

A lot of people may find this controversial: I believe the Fifth Amendment right against self-incrimination includes the right, short of perjury, to eliminate or obfuscate evidence.

The answer to this, I believe, is:

The suspects have to come out sometime. Make the arrest in the Piggly Wiggly parking lot, read them the warrant on the spot, and the send the search team to the (empty and unsanitized) house.

[zeugma]

You forgot #6. Bad guy sees cops at door and flushes contraband and down toilet while police wait outside.

If the "contraban" is small enough that it can be so easily flushed, then my answer is "who the hell cares"?

If the police were competent, they could guard against this by putting traps between the street and home or elsewhere to 'catch' the forbidden item.

Of course, dead citizens are just the price we have to pay for the "war on drugs".