What is the general principle of exclusion in the context of disposition evidence in criminal cases?

The general principle is stated in R. v. B.(F.F.), 1993 CanLII 167 (SCC), [1993] 1 S.C.R. 697 at p.730: The basic rule of evidence in Canada is that all relevant evidence is admissible unless it is barred by a specific exclusionary rule. One such exclusionary rule is that character evidence which shows only that the accused is the type of person likely to have committed the offence in question is inadmissible. As Lamer J. (as he then was) wrote for this court in Morris v. The Queen 1983 CanLII 28 (SCC), [1983] 2 S.C.R. 190 at pp. 201-2: Thus came about as a primary rule of exclusion, the following: disposition, i.e., the fact that the accused is the sort of person who would be likely to have committed the offence, although relevant, is not admissible. As a result, evidence adduced solely for the purpose of proving disposition is itself inadmissible or, to put it otherwise, evidence, the sole relevancy of which to the crime committed is through proof of disposition, is inadmissible. (ii) Admissibility of evidence which tends to show criminal propensity