Worse evolving opposite meanings is a real problem. Another example that became popular this century is 'entitled'. Now it means both 'being entitled to something' and 'wrongly thinking you're entitled to something'. So now a word we don't have a simple alternative for is less useful because it has become ambiguous. It also retroactively makes past uses ambiguous. This has a real cost to communication and the remedy is to enforce style to avoid it happening to other words.