Pluralized uncountable nouns are a pet peeve of mine. The one that’s most frequently publicly wrong is ‘equipments’ because it’s posted at every construction site, and there are a lot of construction sites.
cuisines (meaning ‘dishes’)
I’ve also noticed uncountable nouns being used in the singular, which is just as wrong.
a bread (meaning ‘a bun or roll’)
a paper (meaning ‘a piece of paper’)
There are many words that are countable about half the time and uncountable about half the time, which I’m sure doesn’t tend to help people to understand the underlying distinction.
effort / efforts
content / contents
experience / experiences
praise / praises
detail / details
instruction / instructions
input / inputs
dialogue / dialogues
Recently I saw an email from a marketing agency in which the text of the ads was referred to as ‘ad copies’ instead of ‘ad copy’. Ack, no.
Fighting such errors may be impossible in the long run, because in principle there’s no reason you shouldn’t be able to say ‘equipments’, and obviously people here already feel perfectly free to do so. Until uncountable nouns die off completely, though, you’re better off knowing how to use them correctly.