It is normal for any hydraulic shock absorber to have a light oil film on top due to normal air exchange. Don't mistake it for a leak. Under normal conditions, most shock absorbers used on Honda vehicles will last a long time without replacement. More often than not, the common cause of poor ride quality is tire wear rather than a suspected shock absorber failure.
Although each shock absorber can be replaced individually, it is recommended to replace in pairs (both front or both rear) to ensure the same response on both sides of the vehicle. The springs can only be checked after they have been removed from the vehicle. There is no easy way to test spring compression in a garage unless you have a spring tester.