anonymous tips aren't enough for a search warrant. the supreme court has supported this.
if someone's smashing a door in it's because they have a warrant, and there are judges who are more linient than others in giving those out.
there are cops who'll lie to get a search warrant. like the following:
[youtube]EHmP_KtmcB4[/youtube]
this is an ex-cop who got tired of the corruption. one day, he decided to 'reverse-sting' the police. he set up a grow light with some pine trees under it. he set up hidden cameras within the house. then he called in an anonymous tip that marijuana was being grown in the house. the cops had lied on the affidavit saying a undercover had bought marijuana at the house, and that he had seen a gun (it's been a while, so i may be off a little on this part). when they executed the warrant, they found an empty house, no guns, no marijuana, just a grow light (LEGAL) with some pine trees (LEGAL) and a note on the wall that says everything at that house is being recorded, it was a reverse sting on the police. a tech girl finds recording devices and then the transmitter, she tells everybody to be quiet and exit the house. and that's when the recording shuts down, because it was being transmitted to a near-by van, which had to drive out of range.