EDIT This is what you get to represent invalid data.

(i.e. Since the Latin1 0xDF (ß) is invalid UTF-8, a correct thing for a display system to do is send the old black diamond [◆] with question mark [?]. )

Cruizing around in Firefox will show you more of these than MSIE, which tries to guess the intended encoding of pages.
 
ADD NEWSIMILAR CHARACTERS
 < CHARACTER >  BLOCK PROPERTIES
U+FFFD REPLACEMENT CHARACTER
DEUTSCH : ENGLISH