It can also be a problem if a dog is born with very tiny ear canals. Since you have a Frenchie, floppy ears are not an issue, but if you have a Frenchie crossbreed whose ears do not stand up ...

if there is a lot of wax build up in there or they are particularly smelly then these could be signs that your dog has got an ear infection in which case I strongly recommend a trip to the vet's ...