Ever since I started using the Akismet plugin for WordPress I rarely if ever get any spam. You can see from the chart below it has caught over 1,000 spam attempts.  I also use the math question on the comment form so bots can’t just submit the form – that has also helped out a lot.  The great thing about Akismet is it catches it when its a manual submission by some spammer.  I have however found about 5 comments that were legitimate in the spam bucket.  The chart below is generated by the Akismet Stats plugin in the WordPress dashboard.