Mulla's Conundrum - When a Contract Becomes a Nuisance

I'm at 2am, still trying to wrap my head around Mulla's Conundrum. So, according to law, a contract is a legally binding agreement between two parties. But what about when one party is just plain annoying? Like that uncle who always shows up uninvited to family gatherings. Can you sue them for being a nuisance? Apparently, in the 1973 case of R. v. Kaffel and Co., the court ruled that if a contract creates a nuisance or interferes with the legal rights of another person, it can be unenforceable. But what about if the nuisance is just part of the deal? Like if you hire a noisy street performer and you knew they'd be loud? Can you sue them then? Maybe, if the noise is causing a significant disturbance to others. But what's 'significant' anyway?