There is a difference between kissing someone's feet, trying to suck on one of their toes, kissing the neck, grabbing the ass etc., I also don't think you ask those things, you let it evolve, you go for it and see what happens. However, when it comes to something like CIM, unless you know it is standard procedure, I would not suggest that someone just go for it, the rest of the session, if there is any at all, may not be too enjoyable if that is something that is not on the menu. Of course, if a person does his/her research, he/she should have a good idea of what is available (PC nod to Lopaw).
Another example that comes to mind is that sometimes when I am working on under the hood, checking fluid levels, etc., I may want to use my fingers. Now, if I am going to do FIV, I would rather ask somehow and be told to proceed or not rather than having my hand swatted away or being kicked in the head or having the lady pull away. There are some things where I think verbalization is best, at least IMO.
For the OP: there is also a difference between a little foot attention and a session in which you play with the feet for a substantial part of the session, that is why I suggested an ISO, assuming that is what you are referring to. As for the post below stating that it is alright to ask about different things as you are communicating prior to the date, that is OK if you contact that particular lady, but as a general policy, my guess is that 99 out of 100 ladies will cut contact off with you the minute you are explicit about a particular menu item. Note also that your profile, including personal statement, if you belong to P411, give you an opportunity to verbalize what is important to you.