Forms - Honeypot - Still getting spam

We use the honeypot method on clients Perch forms to combat spam, however, we are still seeing spam coming through not flagged as spam so the spam bots must be doing something on page as they are not entering the honeypot field. I assume the spammers are not sitting there manually entering the form so what else could be happening and is there anything else we can do to stop it.

Would Akismet resolve this? At £4 a month I doubt it's a viable option for most clients.

We don't wan't to use Captcha or challenge questions as for us it's making it more of an effort for genuine form users to submit an enquiry. So is it just a trade off in having to deal with the spam that does get through?