$ldqm = encode 'UTF-8', decode 'Windows-1252', encode 'UTF-8', $ldqm;

   $ldqm                 => 201C
   encode 'UTF-8'        => E2 80 9C
   decode 'Windows-1252' => 00E2 20AC 0153
   encode 'UTF-8'        => C3 A2 E2 82 AC C5 93
[download]

$rdqm = encode 'UTF-8', decode 'Windows-1252', encode 'UTF-8', $rdqm;

   $rdqm                 => 201D
   encode 'UTF-8'        => E2 80 9D
   decode 'Windows-1252' => 00E2 20AC ????
   [error handling]      => 00E2 20AC FFFD
   encode 'UTF-8'        => C3 A2 E2 82 AC EF BF BD
[download]

Windows-1252 doesn't have a character defined for 9D, so when you decode('Windows-1252', "\x9D"), you do something irreversible. The following all result in C3 A2 E2 82 AC EF BF BD.

• U+2001 EM QUAD
• U+200D ZERO WIDTH JOINER
• U+200F RIGHT-TO-LEFT MARK
• U+2010 HYPHEN
• U+201D RIGHT DOUBLE QUOTATION MARK