The standard for probable cause is well above the “I felt like it” level. It explicitly requires that an officer of the law be able to express a cogent probability that a crime has been committed. It takes a judge to hear the officer’s statement and agree that it is “enough” to warrant investigation.
In other words - it takes a modicum of time to make sure that whim is not the standard for search and seizure.
Having the judge involved helps to defray the rationalization of an illegal search by the police.
“I smelled a smell outside the apartment next door to a dope dealer, and there were sounds of people inside, who didn’t open the door when we knocked” doesn’t sound to me like a reasonable level of probable cause. But maybe I just expect the rules to apply to every one.
If someone testified to a judicial official that they smelled the odor of marijuana coming from an apartment, it would absolutely be enough to establish probable cause for a warrant to search that apartment. See United States v. Harvey, 961 F.2d 1361, 1363 (8th Cir. 1992); See also Horton v. Goose Creek Independent School District, 690 F.2d 470, 477 (5th Cir. 1982); United States v. Barry 394 F.3d 1070 (8th Cir. 2005).