How do you express them?

[peppy_man]

I'd like to know how you express the people who slur (or put down) others, famous people or some products on the internet.

I can't find any good expression, though I know that kind of deed is called 'slurs on the Internet'. 'Internet slurer(s)' is OK?

[Mister Micawber]

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'Trolls'?

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