source of negativity

there is a program that measures sentiment of listing descriptions. sure thing, I have positive impression all through but one of my item appeared 99% negative. I blamed the word 'black' in the description (but what have I to do with the existing color?!). then, I had the second item with the same story: it's description is full of eh... 'negativity'. Among almost 150 listings there was NO ONE with such a bad impression. for a machine, that is. I gave the descriptions to real people, and they could not find any negativity, so I blame the machine imperfection. or the word 'cross' being in both listings :))))

they are both in the jewelry for men section in my store.