I've seen a lot of posts here about greying out or hiding controls and menu items, but this question is about greying out or hiding informational icons in a selection list.
I'm curious on your thoughts on greying out versus hiding an icon (to represent a service) in a selection list. Let's say we have a travel itinerary with two legs. Each leg of the trip is identified by a number, and icon for the service and the origin/destination. A user can select via checkbox, which legs they want to use this service, if available. So for this example one leg has the service, the other does not – the reason it does or does not have the service is not important in the decision, and additionally, the service may or may not be available in the future on this leg. Currently, when the service is not available, we are disabling the checkbox (to 40% grey) to not allow that leg to be selected. The question is do we also grey out the service icon or remove it completely (keeping the space it occupied open, leaving gap) in the table view.
It's (I think) a well known standard that unavailable, disabled or otherwise non-selectable items are greyed out. Hiding icons I have not seen very often, and my initial impression is that something is missing, but it's unclear if it's missing the service or the page is broken.
I'm interested to hear your feedback.