Here is the item again:
For example, sand-encrusted feet or a cold drink in a sweating bottle.
You correctly identified the fragment as an afterthought. For example, the transition that begins the phrase, is the clue.
To fix this fragment, you could add a subject and verb, like this:
For example, Geraldo will not
tolerate sand-encrusted feet or a
cold drink in a sweating bottle in his new car.
Or you could use Punctuation Rule 7:
Main clause + , + afterthought transition + Ø + details.
The correction would look like this:
Geraldo will not tolerate anything messy in his new car,
such as sand-encrusted feet or a cold drink in
a sweating bottle.
Notice that for example has become such as. It is best to save for example to introduce a main clause. If the afterthought comes at the end of a main clause, change the transition to such as, like, or including.
Enjoy the sound of those bells!