The API seems to have a little problem.
When strict mode is off : http://api.deezer.com/search/playlist?q=vieille%20charrue
When strict mode is on : http://api.deezer.com/search/playlist?q=vieille%20charrue&strict=on
According to the documentation, when the strict parameter is set to "on", the fuzziness must be removed.
In fact, there is no fuzziness when not using this parameter ( or if strict mode to "off" ) and the fuzziness is added when I set this value to on ...
Seems to be a small bug, am I wrong ?
Using the strict mode allows you to correct the spelling of your search.
Hence, ?q=vieille%20charrue will return no data since there is no playlist called 'vielle charrue'.
However, if you add an S like this : http://api.deezer.com/search/playlist?q=vieilles%20charrue , you will get the same result as http://api.deezer.com/search/playlist?q=vieille%20charrue&strict=on
Does it answer your question ?