I don't think it is directly supported as a feature yet. But you should be able to circumvent the clutter problem by defining your "unwanted" tasks in a separate GCal calendar (which you would normally keep hidden in GCal) and use Doit's "reverse sync" feature to import this calendar's tasks into Doit.

A simple and more proper solution would be, for example, for Doit to implement a checkbox called Calendar when you create a scheduled task. The default should be "off". The vast majority of "scheduled" tasks are not GTD Calendar tasks at all but just regular GTD Ticklers ("irrelevant before" this date, but not necessarily to be done on this date unless it also has a deadline on this date.).

@Amodo
Hi,

Yes. It is not supported to ignore certain tasks for Google Calendar sync. You can select calendars. Maybe you can move your daily repeating tasks to one calendar in Google Calendar and do not select this calendar to be synced to Doit.im.