Are all dreams involving the deceased truthful visions that we should take heed of, even if they occur in broad daylight, given that the deceased is in the Abode of Truth?

Visions and dreams, whether by night or day, are not to be built upon. They can be truthful or untruthful, and there is no difference between seeing the deceased or anyone else. The fact that the deceased is in the Abode of Truth does not mean that everything related to them is true and accurate. Visions may stem from the beholder's attachment to the matter, or from the devil's tampering, or for other reasons.