if it didn't kill the dog, it was probably alright. dogs eat by smell and not taste. most all food had enough protein but the fat content varies from 8 or so up to 30 or so. dogs need the fat for energy, my dog's sleeping on the couch don't need much. then figure out whether you want to use corn and wheat base or use the one's using other grains like barely, rice etc. read the the labels. the food is listed in order of importance, ie: quantity. they don't tell you a lot but then that's all you are going to get from the mfg. some meat as first listed is nice, chicken by products probably means eye lids, beaks and butt holes, kinda low grade. you can go online and pull up more on dog food than you are going to want to read and then come away confused. this is ol' hat for most of us but then you if took a survey of what we are feeding, you would need several beers.
corn is likely low rent and used to be a lot cheaper, now that corn has gone through the roof, it cost nearly as much as some of the better food. most dogs however have done just fine on the stuff and that is what most dogs get to eat. don't buy the big name brands just cause you think they are good, they probably are good but also overpriced, hell, ask your dog
cheers