I use iCal's month view, so when creating an event I put it as all-day and put the event time in the title, like so: "3:30 meeting with Steve", "9am-10am TYO-NYC flight" (if you find it unusual, I'm not the only one doing this, and this style has benefits such as when dealing with time zones). iCal promptly removes the time from the title and changes the event from all-day to the new time, so I have to edit it again.
Same thing with Reminders application. Even more annoyingly, if you put a link containing a date (eg. http://www.tofugu.com/2013/06/04/how-to-write-letters-in-japanese-an-introduction/), it will convert this to a "remind me on this day" date as well.
It looks like it cannot be turned off anywhere in Preferences, but maybe there is a setting accessible from the command line?
(So far I found only one suggestion online, and it was to type the date twice - iCal will remove one date, but keep the other. While this works, it's annoying and you still need to change the even back to "all-day" and I hope there's a better way.)
I'm running Maverick with all the latest updates.