I'm increasingly irritated by search engines returning results I'm not interested in, and Amazon are just another example. If a search returns no result, I want to know that instead of having to plough through the vast swathes of useless results just in case the one I want is actually in there somewhere on the 10th page.
When I use + and quotes on a Google search string, I just wish they'd actually pay attention to that. Instead more often than not they they present a bunch of pages that actually do not feature the words I've supposedly specified as being compulsory in the search. Not useful at all. I long for the days of Alta Vista which simply did nothing more than straight string matching, not some hocus pocus bullshit algorithm whose only purpose is to encourage me to view pages that I already know I don't want to see.
Search engines have become the lazy answer to poor organisation and maintenance of data, and there's plenty of services out there like Google, Amazon, Bing, etc. that exploit that laziness as an excuse for pushing adverts. Microsoft's help is appalling these days, where pressing the help button on an in focus dialog box generally fails to being up the help page for that box.