Having said this, a "lowball" offer is purely a matter of seller perception, and buyer's motivation. There really is no determining factor of what may be viewed as a lowball offer with any one seller. Keep in mind that, even if you submit an offer that is lower than asking price, you may have included certain terms and conditions in your offer that strengthen your offer and may be attractive to the seller, even though you have not met them on asking price.
If you are considerably lower than asking price, and have not built anything into the offer to appeal to the seller, they may or may not consider the offer depending on how motivated they are to sell.
In any instance, if you are struggling with your decision, you should consider consulting a real estate professional in your area to represent you as a buyer's agent. They can help you negotiate the best price, in the shortest time, with the fewest hassles. If I may be of any assistance in recommending one in your area, please do not hesitate to contact me!