Unacceptable

German, it is a commonplace, sounds rather hard-edged and spitty to English natives, but be that as it may, its pronunciation is a marvel of simplicity. Once you've learned the alphabet, you can read aloud with ease, confident that there are no traps lying in wait. This is not remotely true of English.

There are two standard pronunciations for a doubled "c". Sometimes it's pronounced "-k-", as in "accompany" and "staccato", and sometimes it's pronounced "-ks-", as in "accidental" and "eccentric". (In a few words borrowed from Italian, it's "-ch-", as in "bocce" and "capriccio".) If you don't know which is which, you're out of luck; but the pronunciations can be learned, and the learner can be sure that those are the only possibilities. (There are guidelines: "-cce-" is almost without exception "-ks-" and "-cco-" is always "-k-", for instance.)

So what the hell happened to "flaccid" and "succinct"? Somewhere along the way, in the popular mind, their doubled "c" came to be pronounced as if it were an "s". If you are a descriptivist grammarian, then you may blandly note that this is simply how the words have come to be pronounced. But if you're me, if you have some standards, you'll snarlingly note that there are still only those three pronunciations for "-cc-", that "-s-" is not one of them, that "flaccid" and "succinct" are correctly pronounced in the "-ks-" mode, and that careful speakers would not dream of having it any other way. Period.