Signing up for lists

How many email marketers hand over email addresses whenever asked? Are those of us in the email field more or less likely than the average consumer to sign up for something?
I sign up for a lot of mail, but there are different categories of that mail.
Mail I actually want from a company. Usually these are local companies where I visit their brick and mortar or an online only company that I actively buy from. I read the emails for the content and because I’m interested in the company and their products. I occasionally will actually analyze their headers and think about their sending practices. Usually I’m just interested in the sale they’re offering or the information they’re sharing. These companies get a tagged email address that goes into my main mailbox.
Mail where I’m interested in how the company is using email. Generally these are big, national brands. Sometimes they’ll ask me for an address during an offline transaction, other times I’ll make a purchase from. I’m not really interested in what they’re offering, but it’s good to keep an eye on how email is being used by large companies with expensive ad agencies and marketing departments. I do look at the headers of the mail, check their authentication and look at the format of the emails. These companies also get tagged address that goes right to my main mailbox.
One thing I don’t do is automatically provide email addresses to companies. This annoys some to no end. “We don’t have an email address on file for you. Do you have an email address?” They never ask if I want to give them the address, they just ask if I have one. I expect a lot of people just say, “Yes, it’s laura@example.com” and don’t think for a second this means they are opting in to mail from that company. I also think that some companies train their phone and sales reps to ask this way in order to get email addresses from people without informed consent.
I also do a lot of signups to client lists. This is mail I want as without copies of the email I can’t do the audits they’ve contracted me to do. I have a set of addresses that go to a special account and are automatically tagged with client and signup information so I can sort and filter by client and website and all sorts of fancy things. I spend a lot of time looking at the structure of the email. I look at headers for compliance with standards and to confirm any authentication is set up correctly. I look at the body for similar reasons.
I also sign up for some mail that I don’t really want to receive. For these classes of mail I have disposable addresses. This can be investigating affiliates (or potential affiliates) for clients. This can be for an ESP client who wants one of their customers investigated. Sometimes I can’t believe a website is for real so I sign up just to see what their hook is.
Using different addresses and different filtering schemes helps me keep all these email uses separate and clear. I can tell what category a mail is in just by the address that it was sent to. I can also filter on “To” addresses, meaning that mail I’ve signed up for doesn’t get caught in my spam filters. Complex? Yes. But it keeps me up to date not only on offers from companies I purchase from, but also on what others are doing in the email marketing world.