An unqualified or clean opinion is the norm and says the statements are fairly presented in all material respects. Anything else, whether a qualification, a disclaimer or an adverse opinion, is rare and serious.
Modern reports also list critical audit matters: the areas the auditor found most difficult and judgemental. That list is a free, expert-written map of where a company's earnings-quality risk actually sits, and very few investors read it.
Example: Northwind's auditor issues a clean opinion and flags two critical audit matters: the valuation of the Cloud reporting unit's goodwill and the warranty reserve estimate.
Related: going-concern, restatement, earnings-quality, form-10-k, footnotes