What is the test for a motion for a mistrial?

We review a motion for mistrial for abuse of discretion. A trial court should grant a mistrial only when a party's chances of receiving a fair trial have been irreparably damaged, and we use the deferential abuse of discretion standard to review a trial court ruling denying a mistrial. [Citations.] [Fn. omiited.] (Blumenthal v. Superior Court (2006) 137 Cal.App.4th 672, 679 [40 Cal.Rptr.3d 509] .) [T]he trial judge, present on the scene, is obviously the best judge of whether any error was so prejudicial to one of the parties as to warrant scrapping proceedings up to that point. (Id. at p. 678, 40 Cal.Rptr.3d 509 .)