We cannot decide if it is right or wrong and claim it as fact. It is really dependent on the spell you are performing especially if it was made by someone other than you. Honestly, I wouldn't go around and replacing items in a spell that aren't substitutes for each other because it has the potential of failing or bringing upon different effects.
Items help influence and add on that extra energy to a spell. It gives it that extra boost. Of course, different items have different effects. You wouldn't want to go around and use elderflower to attract love when it is actually meant for healing. lol. Would you?