You have to read all the ingredients before trying any of the liquid smoke products. I bought some of this:
The Lazy Kettle brand of liquid smoke is made differently. Hickory and a little mesquite are burned at a low temperature, then the smoke is captured and diverted into a tunnel, says Lawrence Ames, president of Honest Foods. In the tunnel, a constant stream of distilled water is channeled through the smoke to pick up the flavor. The liquid is then filtered to remove any sediment or oil before bottling. There are no additional ingredients.
It's very clean (so it won't gunk up your atty or lungs) and very concentrated, so you might want to dilute it in PG or VG first and experiment. Less is more with this stuff. My thoughts? Blech... not even close to smoky tobacco so I used it in cooking and gave the other bottles I bought away as gifts. LOL.
There are several vendors who sell liquids that have a wood smoke flavor added to it as well (usually have the word "wood" in the flavor like Applewood). Not my cuppa tea either.
If you really want to check it out, see if Flavorart still has a liquid smoke DIY flavoring so you'll know it's safe for DIY. I know they did sell it a few years ago. Not sure which vendors are carrying it these days (I stopped doing DIY), so you'll have to search the forum.