49+ Black Spots In Avocado. Another possible sign of rotting is dark streaks in the flesh. If the spots are relatively mild (and brown, rather than black), give it a taste test.
Cut them out and carry on.
As for the strings, i find avocados with strings in them have deteriorated in flavor and do not taste good, so i. The avocado is edible, but may not taste as good. If an avocado is already ripened at the store there's already a high probability it's been handled explains why some over ripe avacado i've used for guacamole were stringy. If the avocado has only slightly rotten parts inside, it's still good to eat.