Problems with character sets when blogging

This post is primarily to test Feedburner which gripes about strange characters. Some of my material comes from other sites such as the publisher’s web pages that I have been analysing recently. These contain all sort of strange material such as scripts, character entities, etc. and I normally simply cut and paste them. (I can’t easily see any other way). Sometimes the web cruft destroys the post completely, sometimes it spills over into another post following it on a Planet, etc. I don’t know if there is a way of santizing this – e.g. paste into another web page offline and run it through HTMLTidy or something?
While I’m on techie stuff ocacsionally stuff goes into the blog spambin. I skim this very rapidly – ca 300 mails/day and I caught a mail from Egon today and saved it. No idea why it got there.