I will also disregard any internal polls, particularly in downballot races.
Last year, there were two special legislative elections in the same North Jersey district - one for the Senate and one for the Assembly. The (appointed) incumbents were both Republicans.
In mid-October, the Democrats claimed that they had internal polling showing their Assembly candidate up by double digits and their Senate candidate leading by an unspecified amount:
https://www.insidernj.com/insider-iline/keep-eye-bucco-2020-volatile-morris/Ultimately, the GOP won both races, with the Senate candidate winning by 8 and the Assembly candidate winning by 5, even as Biden carried the district by 9.
This is not some WWC area full of low-propensity Trump supporters. It is a wealthy and well-educated suburban district, and yet the internal polls turned out to be complete BS.