I\'ve got a database with a bunch of broken utf8 characters scattered across several tables. The list of characters isn\'t very extensive AFAIK (áéíúóÁÉÍÓÚÑñ)
Fixing
You might have rows with properly encoded UTF8 and with wrongly encoded characters. In this case "CONVERT(BINARY CONVERT(post_title USING latin1) USING utf8)" will trim some fields.
I ended up doing it this way
update `table` set `name` = replace(`name` ,CONVERT(BINARY "ä" USING latin1),'ä');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "ö" USING latin1),'ö');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "ü" USING latin1),'ü');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "Ä" USING latin1),'Ä');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "Ö" USING latin1),'Ö');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "Ü" USING latin1),'Ü');
update `table` set `name` = replace(`name` ,CONVERT(BINARY "ß" USING latin1),'ß');