Breaking News: Nipping isn't necessarily naughty...
Did you know that nipping is a way your horse can be seeking to connect with you?
While we are looking for more subtle cues, your horse nipping at you can be their efforts to get your attention and focus on them because they want you to be with them and present. Our nippers commonly are the larrikin type, confident and mischievous and they are enticing us to play back. (Ie does it sometimes feel like a game to your horse when they nip and you smack?)
Another time our horses nip at us is when they are trying to communicate something. An example of this is when we rug them and they are having problems with the rug fit, girthing them if they have ulcers or the saddle/girth is uncomfortable, nipping at us when we try to pick their hooves up because they have a sore back etc.
Big problem is, we are taught that nipping is naughty and we should stop it. But it is how our horses fill their emotional cup and how they communicate.
Rather than reprimanding the action, why not teach them to lick instead?