When you view zoom to 100% you are viewing your Image actual pixels but most likely not at the resolution you will print the image. The displayed image will be different size then the printed image. However, the pixels displayed have the quality you get from your camera and how well your edit you image pixels to maintain image quality. When you zoom to any other percentage you are not viewing your image. You are viewing a different image that Photoshop has created by scaling you image to have a different number of Pixels a different size canvas for you to view. The scaling Adobe does zooming is not done for best image quality using some fancy interpolation method it is done as quickly as possible so zooming will be responsive so you will be happy with Photoshop performance. At some percentages the image quality can be quite poor. However, none of the zoomed images is your actual image. When edit at a zoom percentage how Photoshop applies the edits to your actual image is what counts. You should never judges a book by its cover you should view the actual book at 100% page view and Print it at print resolution you want to judge the image quality at.
If you have a High PPI resolution displaye with a relolution around 300ppi you can judge print quality on you display for the image resolution will be nearly the same printed and on your display.
Other Photoshop features do similar things for example when you transform a layer size the image displayed in the Transform bounding box is a quickly scaled preview. When you commit the transform you will see Photoshop actually perform the actual transform the image quality will improve and be better them the preview you saw when while you were activity using the tool.