Right?? Oh maigad, I hate that! I mean, there are a lot of medical reasons a person can faint and be tired, but damn! They usually look like shit, not like dolled up glamor queens!
Ick! I guess I'm more annoyed by the "no name illness" thing due to being interested in medical stuff. Picking an already existing illness just seems so easy? Sure, the amount of symptoms and how badly you experience them varies from person to person, but they're still normally very by the book. If you can't visualize the issue, there are a ton of pictures and videos you can look at to reference. If you want a character to have specific symptoms, but don't know an illness that would go with them, you can google the symptoms and 98% of the time you will find something.
You want your character to have a condition where they have blue skin? We got you covered.
How about something where the whites of their eyes turn yellow? Here you go.
How about a disease where the flesh just decays off their body? It's gross, but we got that too.
Not bothering to use a proper illness seems so unnecessary, and again, super lazy. Again though, I'm really bias due to being into looking up that stuff, and get some weird enjoyment out of making my deathly sick character look like they're going to kill over at any moment. Sorry for the ranty post!