What is the effect of the "other crimes" instruction in a murder trial?

I believe that the "other crimes" instruction was erroneous under California law. It impermissibly allowed the jury to use the evidence in question to infer that defendant was possessed of a bad character or had a disposition or propensity to commit unlawful acts, and that he conducted himself accordingly with respect to the charged murders. It should not have done so. (See, e.g., People v. Hayes (1990) 52 Cal.3d 577, 625, 276 Cal.Rptr. 874, 802 P.2d 376 [impliedly approving an instruction that "warned the jury not to consider the other-crimes evidence to prove that [the] defendant was a person of bad character or had a disposition to commit crimes" (italics in original) ]; cf. Evid.Code, 1101, subd. (a) [providing that, as a general matter, "evidence of a person's character or a trait of his or her character (whether in the form of an opinion, evidence of reputation, or evidence of specific instances of his or her conduct) is inadmissible when offered to prove his or her conduct on a specified occasion"].) It goes without saying that a charge of this sort should never again be given.