I saw this suggestion in another thread... but I am not sure what is meant by it exactly.
Where exactly do you delete your hitlog (is it the stats page?) and how does this help?
I have been recently bombarded by spam hits in spite of the fact that I have no trackback and they cannot comment... they just use up bandwidth wasting their time trying.
If you want to delete info from the hitlog table, go to the stats page, then look at the Summary subtab. Next to the listing for each day's stats, there's a red X. Click it to delete the stats from that day. You can also set how many days of stats that you want to keep in /conf/_admin.php (or one of the other conf files). And they'll get autopruned. It's set to 30 days by default.
I don't know if it will help with spam, but that's how you do it.