Attention disorders are about a deficiency in executive function, including a reduced ability to control one's attention (as opposed to just being a lack of attention). When disinterested, this leads to an inability to focus/concentrate. When it's something you like, this leads to "hyperfocus," whereby it's tough to pull away and behavior can be obsessive/addictive in nature. This latter symptom seems to receive less attention (edit: no pun intended :)). (And individuals and specifics differ.)
This is an oversimplification and I'm being a little loose with the vocabulary, but I wanted to at least briefly comment on the perceived "sketchiness" you mention.
AIUI, this is a very common but false belief; it is in part based on hyperfocus being a common feature of ADHD, but hyperfocus on something isn’t (though its often mistaken for) liking it. (It’s also probably based in part on “activities” that are themselves tolerant of lack of consistent focus and task switching.)
I love spending time with him on our home server, but trying to keep up with him is sometimes just as frustrating as helping him with math homework.