I've always assumed when people were like "I like an intelligent partner" what they were really saying was "I like someone that can contribute to a topic or conversation even if it's outside their wheelhouse. Sapiosexual is often used to indicate that the most attractive quality to a person is the mind of their partner. Physical appearance certainly plays a factor in it, when it comes to dating or physical intimacy there's always some level of appearance, but the mind of a person is the important bit. On certain dating sites and apps it's also used as a sort of statement against what some perceive to be superficiality, namely the whole 'looks are the most important thing'.

It's kind of a pretentious thing to see on a profile in most cases. 

But sapiosexual people tend to not be attracted to a person from the start, like they don't look at a person and go "Shit, they're attractive I want to sling that D" but rather they build up an attraction the more they get to know them and their mind and they become more beautiful in return. If that makes sense. It probably doesn't because I'm bad at this. Sapiosexuals don't always value a deeply physical intimate relationship either. 

A lot of sapiosexuals seem like the worst people to date though but that's just me being a bitch.