[He drops a chip in his lap while he's waiting. Just because I can. He's very annoyed when the vinegar makes a spot. And naturally pretends nothing happened, taking one of each of the three chips when she gets back and proceeding to answer her question almost immediately afterward.]

A few. A couple of combination-specific and another couple for entirely different bits on the spectrum. This is much better - you should try it. At best they'd sort of compare to your somatosensory receptors, only on a... wider scale. Humans have got a lot more senses than they usually give themselves credit for anyway though - you lot lump them all under the same five headings but there's a whole mess of smaller ones most of you don't recognise.