It also depends if the seller is selling overly high in the first place. It works both ways, lowball and highball.
Say for example if brand new Nikon 50mm f1.8G is $285 from the popular shops like TK Foto/MS Color etc, and the seller sells his used one at $320, how to say the buyer is low-balling when buyer offers $240? Not making up figures but best on observation on BnS threads - there are people selling at $320 (and still unsold) and there are people selling at $240 (and sold within the day).
Whether brand new condition or not, the moment it left the shop and got into private ownership, it lost value.
Another example is people selling old fungus infected lens at high prices, like a recent 105 AIS, that lens is 10-20 years old, mint collector condition goes for around $350, used condition around $250 to $300. Seller want to sell his fungus infected one at $200+. That is high balling. Real value probably less than $50. If buyer offered $100 less, buyer still overpaid, but seller would still claim buyer lowball because he offered $100 less. You have to look at the realistic value of the item.
Ignore the lowball-highball ball ball words. If its a fair deal, take it if you need it. If its an unfair deal, then leave it. Unfair listings seldom sell - the ad posers will be posing every 3 days like doing a part time job. Just check the threads he started and you may see his selling the same item for the past few months, unsold because price too high and his too conceited that people are lowballing him.
If real low balling can always ignore it. You are angry only when you allow yourself to do so.
I recently sold a lens for $300, common pre-owned prices for this lens is $350 to $400. The buyer on the spot still try to ask for $290, I rejected and press the lift door and want to go home continue watch TV, he lang lang buy on the spot. Its common. Its just business.