Mary, liquid smoke is really condensed smoke. Hickory or whatever is
burned green and the smoke condensed out. Would you consider this paleo?
I don't think so, but...

Liquid smoke has all kinds of nasty chemicals in it, as does all smoked
foods, but I own a smoker and use it frequently because I believe
(without any justification, merely intuition) that if we eat paleo then
smoked food is okay and there is a long, long history of eating food
that is cooked over a smokey fire.

--Richard