I had a little discussion with my therapist today. She told me that many times when we think someone is 'reading' us as being a transgender person, it's not really the case. When people look around, they're not playing 'spot the transperson', they are looking first for safe/threat, or friend/not friend. They're just going about their lives trying not to bump into someone else. The thought of inspecting others in detail to see if they are transgender persons never occurs to the vast majority of folks.
Now, if we do something that draws attention to ourselves, making us the focus of attention, then other mechanisms come into play. We get inspected in detail, and if something looks 'off', they we might get read. Wearing a piece of high end formalware to go to the local burger joint might do this, or wearing a large, impossibly complex hairstyle. (Say, a 5 foot beehive dyed blue...)
If we look like we fit in, the momentary looks we get are just momentary looks. It's our own fears that cause us to interpret these as being read. Some guy might let his eyes linger for a second while his teeny testosterone-fueled brain processes... "Girl; cute girl; Do I have a chance with her? ; Ooooh! French fries!..."
There's less going on out there than meets the eye.