[lllllll]

it means you've done at least a little research on what they should be expected to pay and you see somewhere around that range as acceptable. You don't have to tell them that you've researched their rates and find them acceptable

If you find your research is repeatedly off the mark, find better sources.

I'd be very much interested in what are you sources/methodology to carry out this research. I mean, if the company you are applying to is big and well-known ( and listed in glassdoor, angel list, etc), I may have a chance to figure out the rates. However even in the case of known companies, I often cannot find the salary information and instead I'm left with the classic competitive pay/salary/compensation.

Finding out these rates for each company is even harder if you want to be hired as a contractor.