You will see dirt or scratches in focus in the image if there are some on the rear lens, unless its a general fog. If fluid leaked inside the lens, anything could happen, but likely not.
Dirt or scratches on the front are normally not visible, but on the rear, they show up easily.
Use a flashlight to look at it, and also shine the light from the front while looking in the rear, and vice versa to see how much crud is in the lens. There will be some, so don't panic.