Let's consider the following example: a 100-words text containing 10 occurences of a certain keyword. This is probably a clear case of kweyword stuffing.
Now let's assume I can find 9 synonyms or paraphrases of the said keyword and I replace 9 of the 10 occurences of the keyword by those synonyms/paraphrases. So now, with only 1 occurence of the keyword, there's tecnically no keyword stuffing. Or is there? What we have now is a text with 10 occurences of the same meaning - albeit 9 out of 10 are via synonyms/paraphrases. But Google can identify those 10 synonyms/paraphrases and might see them as tentatives to manipulate the ranking.
How safe is it to use synonyms? And: if it is safe now, how long till Google will penalize this as spammy? I mean, today's good practice can easily become tomorrow's grey/black hat technique.
What's your take on this?