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.

Solution 1:

The 2017 aniversary update (Version 1.4) added tooltips to all shop extras which tell you how they affect the consumers. Note that not all effects align with your business interests:

Extras also directly affect the monthly running cost of the shop. This is not shown on the "Items for Sale" tab, but you can see the effect if you switch to the "Finances" tab. It appears to be a fixcost unrelated to how much the store actually sells. Some extras even reduce running cost. For example, adding "some" ice cubes to the Green Slush in the previous screenshot reduces the running cost of that slush shop from $212 to $209.