Naw, they are easy to feed. Flakes, pellets, and frozen foods work just fine. Once they get used to your tank they become fat and come out all the time. Black khulis are the easiest and most hardy.
Never seen a loach eat a plant but they will tear them apart looking for snails, mine did so. The loach will make a clicking sound, this is from them creating a powerful suction to either rip smaller portions of food off to a size they can eat or suck a snail right out of its shell. In my tank they tore the plants apart until all the snails were gone then they left them alone. Others will tell of mixed results as some may continue to search for food and wreck plants in the process, others like me are lucky and they stop the destruction once the snails are gone.
I had 4 young clown loaches last year in my planted tank, and they destroyed all the delicate plants. I originally got them to take care of my snails--they did that in a hurry My amazon sword survived, and anything else that grew really fast. I eventually got rid of them because they got too big for my tank.
Yeah, I've seen people collect them and save them for a "rainy day"...but the bag or tin usually stinks and is disgusting...it's gotta be a pretty rainy day. I just eat em'. I don't like to have em' on me....