This text contains a spoiler based on an image on the cover of a comic soon to be released. Please look away now...
There's a cover with a certain person holding their finger up to their mouth as if to say, "don't tell anyone I'm a skrull". This person is green and has a skrully chin chin. This person has also used thinking balloons in recent history.
I don't think thinking is a clue of any kind. I also don't think green eyes are a clue of any kind. Bendis wanted us to think the baby is a skrull. Maybe she is, maybe she isn't, but a big arrow saying "the baby is a skrull" would have worked just as well as those green eyes. I then took Drew's green eyes as proof she was a skrull, but now it looks like she really isn't. Therefore, green eyes do not mean skrull. Thinking does not mean human (probably)