"Níonn sé a mhadra."
Translation:He washes his dog.
It depends. In Munster Irish, it'd be /v/. In Connacht (and I'd wager Donegal), it'd be /w/
And the Connacht pronunciation would be closer to the 'standard' one?
English speakers learning Irish seem puzzled by this (even disturbed) because they hear their English as "standard" even though there's no such thing. Natives of Alabama, Boston (oops...which socio-economic stratum?!), Yorkshire, Penzance, and Dildo (Newfoundland) all speak English, and are mutually intelligible--most of the time (ha!)-but none can claim true preeminence. Similarly, Received Pronunciation, despite it's fading cachet, is just another variant of English.
That's before we factor in true dialectical variation. Valley Girl English is mostly intelligible to me, while Jamaican Patois English verges on the unintelligible...but both are English.
I find that some comments here from Gaeilgeoirí betray similar local biases and assumptions: "My grandmother says it this way", or, "That's not how we say at home". Yes...well...
Unsurprisingly, my pronunciation of Irish improves if I slip in a strong Newfoundland out-port accent.