Do not forsake certainty for doubt, and what is clear for what is hidden. Do not pass judgement on what you cannot see because of something you are told about it. Allah despises slander and bad opinion of your believing brothers. What then does He think of boldness in attributing a false statement, false belief or lie to the Companions of the Messenger of Allah?

As He said,

When you welcomed it with your tongues, and spoke with your mouths that which you had no knowledge of, and you deemed it an easy matter while with Allah it was grievous. (24:15)

As long as you can find a way to speak well and act well of people whether or not they are present. Do not do anything else. Allah said,

Speak to men good words. (2:83)

Know that Allah chose companions for His Prophet, honoured them with the noblest mark of honour and robed them in the robe of support, victory and the correct keeping of his company in desirable and undesirable situations. He made the tongue of His Prophet speak about their virtues, excellent qualities and marks of honour; so believe in their love, mention their excellence, and beware of the company of people of innovation, for it will make disbelief and clear loss grow in the heart. If the excellence of some of them is not clear to you, then leave them to the Knower of the Unseen, and say, 'O Allah, I love anyone You and Your Messenger love, and I hate anyone You and Your Messenger hate.' There is no obligation beyond that.