For the last while I’ve been using a custom plugin to link to Amazon, not cut and pasting the urls myself so I might have just missed it but is this new? Amazon now has somewhat (barely) cleaner urls with the title and author at the beginning. Check out the ones for Neil Gaiman. One example:
(from a search they add a lot of crap but this short version works too)
Clean urls are when you can pretty much read the url as text, instead of using crazy ass parameters 300 character long.