Fastest way to tell a Pink beside the boat is the larger oval spots on the tail and the very tiny size of the scales.
I have noticed the Pinks off Sooke often have a somewhat darker look to the tail than the other salmon species in addition to the large oval spots. The males often have a noticeably humped back when older and closer to the river and are sometimes called Humpys. Mostly they are 3 to 6lbs but there are the occasional larger ones off Sooke.
They have softer, smaller, weak teeth. If you run your fingers over them hard it does not feel like you are going to cut your finger, unlike Coho and Chinook.
The salmon you are most likely to confuse as a Pink, which is not a Pink, is a small Chinook, however the spots on a small Chinook's tail are smaller and round, not oval. Their scales are much larger as are the scales of the other salmon species not Pinks and their teeth are longer, strong and sharp. Many small Sooke Chinook are clipped, but I have never caught a clipped Pink. The Chinook also have the jet black gums all the way to the base of the teeth..