Can Collicott obtain a search warrant for a methamphetamine lab in violation of a warrant issued without probable cause?

Collicott argues that the warrants were issued without probable cause since unnamed informants were not shown to be reliable and their information was uncorroborated and stale. We conclude, however, that even without the informant's tips, the affidavit provided a substantial basis to support the magistrate's finding of probable cause. See United States v. Yarbrough, 852 F.2d 1522, 1531 (9th Cir.) (appellate review is limited to determining if the magistrate had a substantial basis for concluding that probable cause existed), cert. denied, 109 S.Ct. 171 (1988). The affidavit indicates that the officers were trained in detecting methamphetamine laboratories and that they detected an odor associated with methamphetamine production.