No, it truly is easy if there is probable cause.
This is from: http://legal-dictionary.thefre...
Probable cause is not equal to absolute certainty. That is, a police officer does not have to be absolutely certain that criminal activity is taking place to perform a search or make an arrest. Probable cause can exist even when there is some doubt as to the person's guilt. Courts take care to review the actions of police in the context of everyday life, Balancing the interests of law enforcement against the interests of personal liberty in determining whether probable cause existed for a search or arrest.
If they are not planning to arrest someone, then why the warrantless search? The point is, if the police can articulate their suspicions clearly enough with a modicum of evidence, they get the warrant.