How effective is the honeypot technique against spam?

Question

By "honeypot", I mean more or less this practice:

#Register form
<style>
    .hideme{
        display:none;
        visibility: hidden;
    }
</style>
<form action="register.php">
    Your email: <input type="text" name="u-email" />
    Choose a password: <input type="text" name="passwd" />
    <div class="hideme">
        Please, leave this field blank: <input type="text" name="email" />  #the comment is for text-browser users
    </div>
    <input type="submit" value="Register" autocomplete=off />
</form>

//register.php
<?php
if($_POST['email'] != ''){
    die("You spammer!");
}
//otherwise, do the form validation and go on.
?>

more info here.

Obviously, the real fields are named with random hashes, and the honeypot fields can have different names (email, user, website, homepage, etc..) that a spambot usually fills in.

I love this technique because it doesn't cause the user to be annoyed by CAPTCHA.

Do any of you have some experience with this technique? Is it effective?

Answer 1

Old question, but I thought I'd chime in, as I've been maintaining a module for Drupal (Honeypot), which uses the Honeypot spam prevention method alongside a time-based protection (users can't submit form in less than X seconds, and X increases exponentially with each consecutive failed submission). Using these two methods, I have heard of many, many sites (examples) that have eliminated almost all automated spam.

I have had better success with Honeypot + timestamp than I have with any CAPTCHA-based solution, because not only am I blocking most spammers, I'm also not punishing my users.