Flickr used to apply an auto-enhancement (sharpening, saturation, etc) effect to photos[0]. It would be really weird seeing a photo locally and then see the copy on Flickr that looked better somehow.

Aside: The mention of Technorati tags (and even Flickr) in the linked blog post hit me right in the Web 2.0 nostalgia feels.

[0] https://colorspretty.blogspot.com/2007/01/flickrs-dirty-litt...