In BTD4, this upgrade allows detection of Camo Bloons for any tower in the radius. It is good for those early rounds with Camo Bloons if players don't have any other tower or upgrade that is able to detect them. In Bloons TD 5, this upgrade only allows the Monkey Buccaneer itself to detect Camo Bloons unless a Tier 3 Pirate Cove is active. In BTD6, it is very similar to BTD5 (see this page for more details).
In BTD5 and BTD5 Deluxe this upgrade does not allow Camo detection for all towers, unless a level 3 Pirate Cove is active. This is because upgrades in Bloons TD 5 and Bloons Tower Defense 5 Deluxe that allow Camo detection have changed to only let the tower who bought it be able to detect Camo.
Due to this, if players have a Tier 3 Pirate Cove and a 4-2 Aircraft Carrier, every tower on screen gets Camo detection due to the infinite range of the Aircraft Carrier.