Hybrids are not necessarily bad. There's nothing inherently evil about creating them. The problem is that sometimes the hybrid offspring will look similar to one parent or the other, which can result in them being mistaken for the parent species (i.e., someone mistaking an acara/convict hybrid for an acara). If such a fish were to be bred with other acaras, those offspring can taint the bloodline. Reptile hobbyists have been seeing a lot of this lately, because many commonly kept species of snakes are easy to hybridize. It's a big fat juicy can of worms, but the best thing to do is try to breed true. If you're really interested in seeing what the hybrid offspring would look like, it's your (very serious) responsibility to be sure anyone to whom you give/sell offspring understands that they are hybrids. Some hybrids are actually very attractive — look at flowerhorns.