The caramel/crystal malts add body and mouthfeel along with a little caramel sweetness and color.The darker the more pronounced caramel into raisin, plum favors and lighter candy sweetness. They also help to lower mash ph. Special B is a dark Belgian caramel/crystal malt that adds a raisin aspect. Munich and Vienna are base malts that are kilned a little more and processed a little differently. I use the dark Munich in darker beers, Avangard 15* L up to 20%. I find Vienna to be a little milder and dryer than Munich, I use it in beers I want a little malt presence with some Munich, like APA or IPA or Vienna Lager. Lighter beers I go with a combo of Vienna and Munich. As stated before it depends on your definition of malty, to me it means Munich, Aromatic, Vienna ect. I don't think I would use 20% crystal in a beer unless I wanted something dark with alot of caramel and sweetness. I usually go with 5% in APA and IPA and 10-15% in darker beers but that is a personal preference. Hope this helps.