No, it's not foolish, though it depends on your definition of "lowball" and "overvalued." If you are confident you know its value (either via a Realtor's CMA, or diligent research on your own--NOT Zillow), then your offer should be no higher than, and often lower than, its value. That in itself might be defined as lowball. For example, a house has a true market value of $500,000. It's priced at $600,000. You offer $475,000. Is that a lowball offer? Not really, from the perspective of true value. Maybe yes, from the standpoint of the seller.
There's no definition, of course, what "lowball" means. Like a lot of things, it's in the eye of the beholder. But, to take the example above--house value is $500,000 and it's priced at $600,000--then an offer of $400,000 (20% under value, 33% under listed price) probably would qualify as "lowball." But: So what?
If it's in a hot neighborhood, perhaps the chance of your low offer not being accepted is higher. So then you have to ask yourself how much you really want the house: What's its value to you. Offer more if you really love the house. Offer less if you're just trying to get a bargain.
A lot of questioners on Trulia worry about "offending" the seller with a low offer. Don't worry about it. That's the seller's problem, not yours. Make an offer that works for you. Just understand that, the lower the offer, the lower the likelihood that the owner will say "yes."
Hope that helps.