Android : how to find a rooted device?

I was been trying to find whether a device is rooted or not and if the device is found rooted i do not want my application to get installed.I have tried two of the below methods

private boolean isRooted() {
  return findBinary("su");
    }

public static boolean findBinary(String binaryName) {
boolean found = false;
if (!found) {
    String[] places = { "/sbin/", "/system/bin/", "/system/xbin/",
            "/data/local/xbin/", "/data/local/bin/",
            "/system/sd/xbin/", "/system/bin/failsafe/", "/data/local/" };
    for (String where : places) {
        if (new File(where + binaryName).exists()) {
            found = true;
            break;
        }
    }
    try {

        File file = new File("/system/app/Superuser.apk");
        if (file.exists()) {
            Log.e("ERROR", "Unable to find icon for package '"
                   + "apk found");
       found = true;
        }
      } catch (Exception e1) {
        // ignore
      }
}
return found;
}

But i don't think that these methods are enough to find a rooted device,since there are tools to hide an apk and the su file can be renamed or deleted.Is there any other way or any suggestions which is 100 percent reliable to find a rooted device?thanks in advance