Well, you have to know a few things. First, most lawyers don't have any idea what they're talking about when they write that first letter because a client requested it. They view it as a billable hour, not as a research assignment, and so they write stupid things.
Second, check out this website, which outlines what the real law is. If you've read it, you are more informed than 90% of the lawyers out there, and you have a real basis for understanding what they are entitled to, and what they are stupidly requesting, trying to bluff you into.
There are liabilities to having a profession designed to oppose the society in which it operates. It gets laughable when they describe themselves as public servants.