WowAce

The Guild Page pet needs to be excluded from auto summon, as it has an 8 hour cooldown. (It's a 5 minute vendor.) I only want to summon it manually when I badly need a vendor. There are separate Alliance and Horde versions.

http://warcraftpets.com/wow.pets/humanoids/alliance.companions/guild_page_(alliance).asp
http://warcraftpets.com/wow.pets/humanoids/horde.companions/guild_page_(horde).asp

I'd guess you need an exclude list similar to the favorites list or the list of pets requiring a reagent. One way to implement this is to assign the pet a reagent of unobtanium. ;)

Currently I am against always-exclude lists that are set by me, as it seems to me to assume too much of what people want to do with the app. It is possible for the user to set the pet to never summon.

If there is a lot of call for this sort of thing I will certainly consider it and have created a component to track this and other enhancements that are "maybe but haven't decided"

I started to look through the code to see what would be involved and discovered I could set the pet as a "favorite" with a weight of zero, effectively banning it. I hadn't realized that functionality was there. So perhaps you could add a tip, perhaps under the Favorites entries in the addon description and the readme, that one can exclude or ban a pet by setting it as a favorite with a weight of zero.