Don’t go by blind faith in poll results used in speeches and media. Find out who owns the company and sits on any boards (Bloomberg is informational), also check the date of the poll against the date of the topic referencing the data.
I decided to do this after a Quinnipiac poll taken three weeks previous to the signing of the travel ban was used to state citizen support. My interest in that specifically comes from the difference in supporting a theory that travel bans are necessary, to supporting the actual results of the actual ban which had far reaching affects for families, businesses, and education.
The following link is a decent starting place for your edification.
FiveThirtyEight’s Pollster Ratings | FiveThirtyEight
Make sure you check out methodology. Here’s one example using Rasmussen Poll results, (field work for all Rasmussen Reports surveys is conducted by Pulse Opinion Research, LLC): http://www.pulseopinionresearch.com/FAQ#faq-methodology
And in case you need a crash course, too-