I don't often come across this prhase (I believe it's more common in American English), but when I do, it's often used in a positive sense. I was surprised when I read this entry and it stated that a "double whammmy" has to be a negative event. Sure enough, looking over its usage in news articles showed that indeed the most common usage is with negative events. However, I also found a good number of uses which were clearly positive (e.g. , , , ). Interestingly the last article of that list calls it explicitly a "positive double whammy" suggesting the writer/editor's understanding that the phrase is more commonly used negatively.
It's also interesting to note that all of these positive instances come from UK sources (though the dailymail one is their Indian branch). combined with the fact that my own dialect, in which it's often positive, is Australian English, it might be suggested that Commonwealth usage of the term allows both positive and negative usage, where American English allows only the negative. Of course this is conjecture based on a very small sample size, so it's not really something worth noting in the entry, but still, there's every possibility that there are dialectal differences in usage.
The term 'whammy' feels low, crude and informal. For instance, I would guess that double whammy is not a word used in formal writing, unless put in quotes. It's pushing boundaries in the stupid direction to use it. --Geographyinitiative (talk) 03:36, 11 April 2019 (UTC)