If you are a discipline priest and Grid user you might find GridStatusShields worth looking at. I don’t use it myself as i’m not sure how useful the additional information is, but some people like more rather than less.
According the the description is displays an estimate of the amount of Power Word: Shield, Divine Aegis and even Valanyr procs (Blessing of the Ancient Kings – I wish) on the target, within Grid.
I have Grid set up to display a white dot in the top right of the unit frame if the player has the Power Word: Shield buff. I have Grid display a yellow dot in the same location if the player has the Weakened Sould debuff. I have the priority of the the PW:S buff set higher than the Weakened Soul debuff so the latter doesn’t display if the player has an active shield.
This means I can tell when the player is shielded, when they are not shielded but have the Weakened Soul debuff and when they have neither. I’m am unusually clueless when they have a shield (which lasts 30s) but no Weakened soul debuff (which lasts 15s), but this doesn’t seem to be an issue.
If you don’t use Grid or this makes no sense to you, then just nod politely and keep walking