In this market, I consider “low ball” to be anything under 90% of asking. I never offer less than 80% of asking. That is a waste of time IMHO.
But asking has many flavors. If the house has been on the market >90 days, asking is “likely” to be more reasonable with respect to market conditions. If it is just on the market, it is far less “likely” to be reasonable. There are exceptions, of course. Sticky fickle sellers.
But an 80% offer on a house just on market is a waste typically. You do help the seller get a feeling for market conditions. An offer like that can help with that, but it would not help you, the buyer, get the house. At least with that round and if you do piss them off with it, when you do come back after they have come to their senses, they may, out of irrational seller pride, refuse to deal with you. You have to time your insults in this game, for when they hurt you the least.
But an 80% offer on a house 250 days on market is a different story. However, if it has had price reductions along the way and is close to market, maybe a 90% offer is more appropriate.
Either way, the offer should have logic as to your desire to purchase the house. If I love a house, I am close to 90% every time for the types of homes I go after, usually on market for a while with a few price reductions. That way, your 90% offer may be 70% of original asking.
I note that the really great great houses don’t stay on the market very long, even in this market. I lost one recently that was on market 2 weeks with 4 offers because I refused to break my 90% rule, but the price it sold for was just $50k more than I offered and worth it, even in this market. I made a mistake doing that, the only mistake I fell I have made after nearly a dozen offers. Not bad it seems, but it only takes one mistake to feel like a complete idiot.
So low ball is relative and I certainly no longer worry about pissing anybody off. I put as much logic behind my offers as I can and if that pisses a seller off, it is my fault for not anticipating that. I should make an offer that I know the seller will consider, not that he/she will tell me to shove. There is a way to low ball with kindness, which is often found in the form of objective evidentiary support for your unkind solicitation. Some sellers do respond to logic and reason, some.