When I think of laser rot I think of a small white streak. Sometimes it can even be bigger and take up almost a whole line.
When I think of a dropout it's almost the same but is a solid line of pixels and kind of matches a color near to the dropout or is black.
When I think of dirt I think it can be almost any shape or size or color.
If this is true then there are very few dropouts in the capture but there is a little bit of rot.