Recently I tried to update a Google Play Store listing that contained text something like this:

keywords: apple, celery, cherry, potato, oatmeal, juice, milk, peanut butter, beans

But the Google Play Store said this was a violation of their metadata policy. It took a while to figure this out, because those keywords had been in that store listing for more than a year without incurring a violation. In any case, the morale seems to be: avoid these kinds of word lists in the full description of your app.