All resources, whether they are Open Educational Resources or those which require by individuals or institutions, require assessment to check they meet your teaching needs. Similar criteria students apply for evaluating information could be applied to assessing OERs.
Authority Accuracy Currency Relevance
Authority - who is the author or creator of the information and what are their credentials?
Accuracy - is the information accurate?
Currency - how up to date is the information?
Relevance - will the information be useful for your teaching requirement?