mlistFile (or possibly mlistDir) is probably the API you are looking for to call on the remote directory. That returns an FTPFile object that has the permission info. Of course these will only work if the FTP server supports RFC 3659 extensions.
So something like:
FTPFile remoteDir = client.mlistFile(client.printWorkingDirectory());
if (remoteDir.hasPermission(FTPFile.USER_ACCESS,FTPFile.WRITE_PERMISSION)) {
...
}