They seem legit, though rat leaning (they partner with the Slimes). But I wonder if they have the same issue as Quinnipiac, (less accurate the further you get from CT, it would be NY in Siena’s case)
The sample was 500 likely voters and it’s the first poll in that district that I know of. The margin of error is huge, 9%.
https://www.nytimes.com/interactive/2018/upshot/elections-poll-mn03-1.html
They list different turnout models, all with the rat ahead. The rat leads by 5 under “The types of people who voted in 2014” which I find unlikely.
They admit “It’s just one poll, though. There are many ways it could be unrepresentative of the district in November.”
Don’t buy this MN poll. PPL in MN think Paulsen is in good shape