Guinea pigs make great pets and if you keep them and their home clean they do not smell. My daughters and I raised to guinea pigs and loved having them. They can be trained for a litter box like a cat and are great fun.
Not if cleaned every day to every other day or spot cleaning every day and then a full cleaning once a week. I have three and they don't stink! I take care of them properly the other people who say they do clearly never had one or just didn't clean them regularly