I have a view that displays the results as a table, and also contains an exposed taxonomy filter. I need a way to know when a certain field in a row has a value that has already been "seen". A row with a "seen" value is less useful compared to "unseen" rows. Therefore, the table needs to visually distinguish between seen and unseen rows, perhaps by highlighting seen rows, or fading them.
How could I determine when the field has a value that has been "seen", and then style rows with a "seen" value differently?