I tend to be either hyperfocus or no focus. I can't focus at all if I'm not interested. I am almost as incapable of focusing if I have an obsession I'd rather think of. Dry text books, like those we had in school, make it impossible for me to get info out of them; I have forgotten the start of the sentence by the time I get to the end.
I can't focus at all if there is noise around me (unless I'm in hyperfocus mode when the noise starts, then I don't notice anything), and I am very easily distracted.
I also have a high tendency of my mind going elsewhere when I read or listen to or watch something. Sometimes my mind wanders because it gets stuck on something that was said. Sometimes I can't stop myself from reacting to something (like things that make me angry, and so i react and then I have to start again, and then I might react it to it again and so on. It can be animal abuse or indifference to it, or comments in books / movies about "quiet and weird". Stuff like that).
Often I have problems focusing, my mind just drifts. I remember once we taped a 20 something minutes sit com that I was gonna watch later. When I watched it, I was alone, and I had to rewind I don't know how many times to get to see the entire episode. No lack of interest, it was just my wandering mind. Let's say I started drifting off 4 minutes into the show. I realised that I was and rewound it to about the place where I got lost, let's say I restarted it at 03: 30. Then I had about 30 seconds before I got to the place where I had fallen off, but by the time I got there, I was lost in thoughts again. And had to rewind. Guess what happened next? Yep, new rewind.
And don't even get me starting about music, I get lost immediately when I listen to the music I like.
That happens all the time.
For the record, my dx is AS, but I suspect I have ADD or ADHD-PI as it's called now.