Color that will hit your audience over the head and grab their attention, whether they like it or not. You add red, green, some blocks of blue. You've always liked orange. By the time you're done, your slide presentation looks like a circus. Instead of livening your slides and emphasizing your message, you've wound up with a muddled mess.
Some colors work together, others fight against each other.
Establishing sound relationships is key. Color is never viewed in isolation, but is always judged in its environment. It is influenced by its neighboring colors. For example, place a bright yellow ball in a child's nursery, and it will fit right in. The solution is as simple as turning your head and looking out the window.