Shops in Planet coaster - How do shop extras effect the shop's appeal and the consuming peep?

In most shops, when setting the price of each item, theres a little hidden section below each item that allows extras to be set on that item.

Example: Cosmic Cow Milkshakes offers three products: vanilla, strawberry and chocolate shakes, each has three "extras" (marshmallow, fudge and something else) each with a value out of none, little, some, lots.

I've seen scattered reports about ice in gulpees reducing the effect on thirst, and salt on fries actively eating into the thirst meter but i can't find reference to this in game.

EDIT: I have pinged Frontier on Twitter and got reply. https://twitter.com/PlanetCoaster/status/866976964011335681 The reply was basically "They effect peeps in different ways, but there's no docs. We'll see what we can do about that though." They did confirm salty fries make peeps thirsty though.

If anything, this has given me more questions and a thrist for wanting this documenting properly - as I doubt Frontier will supply this in a level of detail that will satisfy me.

Here is my current list of questions regarding this topic:

• What does each shop extras option do? Or at the very least, what possible values can shop extras affect? Appeal and Thirst are confirmed, but it is likely there are more.
• Is there any existing documentation anywhere about this topic based on solid research?
• Do extras effect the product value and change the profit per item or potential max sale value? Do the shop extras eat into profit assuming the item price is not increased?
• Do specific brands/shop types within brands appeal to different guest types in different ways? Do extras have different effects of different guest types?

EDIT: As of 23/6/2017, despite saying they would supply some docs in a forum post in reply to my tweet, frontier have yet to release any docs on this topic.