Some brands of liquid smoke are just smoke and water; some others have other ingredients (caramel coloring, artificial flavoring), and in some brands, there is no ingredient at all with the word "smoke" in it. It's like real soy sauce versus "soy sauce."
I have a bottle of Wright's Liquid Smoke, which I bought after checking its ingredients, of which there are just two listed: water and natural hickory smoke concentrate. One bottle lasts me years because I only use it to add a couple of drops to Crock Pot pulled pork. For a pork shoulder weighting 5 or more pounds, one to three drops is plenty; any more than that is too much. The same effect, I suppose could be achieved by adding a barbecue sauce with a smoky flavor*, but I don't like to add the sauce til after the meat is cooled and pulled; that way each person can add whatever sauce he or she likes.
*But that makes me think, aren't there probably liquid-smokey-like ingredients in a lot of commercial barbecue sauces? Those ones labeled Hickory Flavor, for example? I wonder if we ingest more liquid smoke, especially fake liquid smoke, in various brands of bbq sauce than we think.
If you're talking about taste and taste tests and such, it seems relevant to me to distinguish between let's-call-it natural liquid smoke and artificial liquid smoke. Or if you don't like calling any of it natural, let's say by the first type I mean just water and smoke and no other ingredients.
"Your swimming suit matches your eyes, you hold your nose before diving, loving you has made me bananas!"