It's open season for the flies again and many horses struggle to accept fly repellent, possibly because of the smell but also because we tend to slap it on cold and in a hurry, aiming vaguely inside the ears. Best thing is to make sure that the cream is at body temperature, use desensitisation techniques to work on the ears and just focus on the putting it on the outside edge of the ear rather than trying to get it inside. It'll work it's way in anyway and provide a good deterrent at the entrance to the ear. I used to suffer with terrible ear ache as a child but hated having cold Earrex drops dripped into my ear. A bit of anthropomorphism should make us realise that horses might feel the same way.
"Just to let you know Rose behaved perfectly when I put fly repellent on her today and was completely relaxed about it." SA (the day after the training).