Most people want as much traffic as they can possibly get.It depends on what you are doing with the domain and why you are parking it.Are you parking for hoped revenue?Are you parking it just to try and sell it?Are you hoping to make enough in parking so that it pays for itself?
I've had names that would get 1100 visits a month and no clicks,month after month.I've also have had names that would only get 10 visits a month,but 8 people would click on it almost every month at .75 to $1 a click.Which is better?
30 visits a month is better than 0 visits a month.Some people only buy names with a lot of traffic in the thousands or more,other people buy names because they like the name.
So to answer your question,30 isn't fantastic,but it's a good start.