So since I can’t rely on the returned value of Model::del(), this is what I thought will work until one fine day the application returns a failure when the record seems to be soft deleted correctly.

// some action of a controller
$this->Model->id = (int) $idPassed;
$this->Model->del();

if ($this->Model->exists()) {
    // say success!
} else {
    // say failure!
}

Alas, Model::exists() sets callbacks to FALSE in its find('count') call. So this means no beforeFind nor afterFind callbacks gets executed. This is understandable since Model uses exists() in many places where it needs to reflect true existence. So to get the expected results, we have to set callbacks to TRUE instead.

$this->exists(array('callbacks' => true));