The Ad Preview and Diagnosis Tool allows you to examine why an ad may not be appearing. It can also provide a preview of the SERP (Search Engine Results Page) for a specific term, so that you can see what ads and extensions appear as well as whether your ad is eligble to appear.
It is better to use this tool than searching on Google as it does not impact your metrics by increasing ad impressions.
PPC Management Agency Google Adwords Metrics Ad Preview and Diagnosis Tool