Unless you have your own server with firewalls, there is no way to keep a request from reaching the server-- and from being logged.
:: detour to look up ::
Oh, the BOM. Don't know why I have to look it up every time.
If they are robots making garbage requests, a 404 is a perfectly legitimate response, though you may want to lock out repeat offenders on other criteria.
If, instead, these are human requests with accidentally appended garbage, it's pretty easy to redirect (not rewrite!) them to the garbage-free version. But we'll need a little more information to hammer out the right format.