Is the use of "utf8=✓" preferable to "utf8=true"?

I have recently seen a few URIs containing the query parameter "utf8=✓". My first impression (after thinking "mmm, looks cool") was that this could be used to detect a broken character encoding. So, is this a better way to resolve potential problems with character encoding, or is it just a developer having fun with a hack?

[a2ikm]

へえええ

[o296sm]

よんだ。なるほど度高い。

[cou929]

へぇー