Inline, embedded or linked Style sheets are fine and won't affect search engines.
However, I don't know how/if SEs can read style sheets for spam techniques. For example; I have a page with a bgcolor of white, if then I have tiny white keyword rich text using the font tag, search engines will see this and call it spam.
But, if I have a white background page but use style sheets to redefine the h6 header tag (for example) to be a 6pt white font I don't know if they will see it as spam.
My initial thoughts are that its pretty easy to see an inline style sheet but embedded and linked ones would be more challenging for the SEs to figure out.
Anybody tried this? Maybe, I'll try it and report back.