Some things should just be included and are assumed to be included. Did your car dealership charge extra for door handles or seat belts? Does Taco Bell charge extra for napkins? If you piece out your services too much then people will get confused and they won't call you. $20 for this, $5 for that... It gets confusing. If you offer an interior detail then you should specify what that includes and if there is a particular service they don't want, then they don't have to have it, but your price stays the same. It's like ordering a hamburger and telling them to hold the tomato. The burger doesn't get $.10 cheaper for that. Same price.
The only time that becomes a problem is when they ask for a full detail but don't want it clayed or polished. Uhm... That's not a full detail. That would be like ordering a cheeseburger, but hold the cheese. It's no longer a full detail if you can't do the things required. If you don't offer just a wash and wax, then don't ever hold services that are essential to the results you want to get. I've had it happen a couple times from people trying to get a better deal, but those aren't the clients I want. I'm not doing this for a living, so it allows me to turn away business if doing the job would lower my standards, give others a bad impression of my work, or if the time isn't going to be worth the money.
Anyway, interior details should include vacuuming, carpet cleaning, dash protectant, leather conditioning, and window cleaning. Sometimes they may request 'nothing glossy on the dash' and that is totally fine. There are a lot of products that aren't glossy. Those interior detailers don't often provide a lot of protection, but they do get the job done and they may be good enough. But don't forget there are other low gloss dash protectants that do the job better and customers will love. And not all cars have leather interior, so the extra charge on that comes out in the wash. It doesn't take that much extra time and if you are charging based on how long it takes you do do an interior with leather, then you'll make more money on the cars without it and be fine on the cars with it. It's not worth nickel and diming them on the price.
