An inevitable hassle when having any kind of blog or wiki that allows others to comment is that one needs to deal with spam.
IkiWiki makes it fairly simple to do that. You should follow your site's recent changes page or rss/atom feed. There's a little cross symbol that allows you to revert a specific change, which you can use to easily remove spam.
If you get a lot of attention from spammers, you may want to enable one or two plugins that will help you prevent spam from entering your site.
blogspamplugin is a spam filter that filters away spammer changes to your site. This spam filter is enabled by default when making a blog here at Branchable.
moderatedcommentsplugin allows some or all comments to be held for moderation. If you enable this, you should check the moderation queue, via the preferences page, or via the moderated comments rss/atom feed, which Branchable sets up by default in the default themes.
To enable the plugins, log into preferences, then click on the "Setup" button, and search for the name of the plugin.