What is probable cause under what circumstances will a judge consider in determining whether there is evidence of criminal activity?

"Probable cause exists when, considering the totality of the circumstances, 'there is a fair probability that contraband or evidence of a crime will be found in a particular place.' " United States v. Ocampo, 937 F.2d 485, 490 (9th Cir.1991) (quoting United States v. Rodriguez, 869 F.2d 479, 484 (9th Cir.1989)). Otherwise "innocent" activity may carry special meaning to the experienced affiant and therefore the issuing judge may rely on this experience when making a probable cause determination. United States v. Del Vizo, 918 F.2d 821, 827 (9th Cir.1990).