These things cut both ways, some sellers have a bad attitude, as do some buyers. (I wonder how many of the bad sellers are also the bad buyers?

) Some people are just abrasive, some are nit pickers, some are time wasting tire kickers and think they're super deal makers and will try and lowball everyone, even when a list price is a bargain to begin with. Buying and selling involves dealing with human nature in all it's variety. Expect to run across your fair share of pests, idiots and others from the rich tapestry of humanity. Including some genuine reasonable people.
I never have a problem with someone asking for the weight of a guitar, bass, body, or neck, I get that for some people weight is a relevant issue and manufacturers (except for some in relation to necks and bodies) don't include weight, because wood varies and Fender, or whoever, are never going to say a P bass weighs x pounds, because a generalized weight will almost never be right on a mass produced instrument.
I do think that if a person gets annoyed when asked reasonable questions, then maybe this selling stuff game isn't for them, I do my research, but if I still have a legitamate question, I'll ask. ( I sell stuff from time to time too and I always give as much information as I can, that way I hope to get less obvious questions, though there will always be exceptions.) If I get aggression, I just move on, I'll find the same thing sometime, somewhere else. But it isn't worth getting bent out of shape over the attitude of a difficult seller, or buyer.