Learn Spanish (Latin America): ¿Por qué andas haciendo un foso con mi rastrillo? - Why do you go around making a moat with my rake?

Using estás haciendo (are making) would just be a neutral question about what the person is currently doing. By using the structure andar + gerund (andas haciendo), the speaker emphasizes that the action is happening in a wandering, diffuse, or repetitive way. It translates well to "going around making" and highlights the drawn-out, ongoing nature of digging the moat.

Does the use of andas haciendo imply that the speaker is annoyed?

It definitely can! While andar + gerund literally describes an action that is ongoing but unfocused, native speakers frequently use it to express annoyance, surprise, or disapproval about someone's behavior. Asking "why are you going around making a moat?" sounds much more exasperated than a neutral "why are you making a moat?".

Could I use ir + gerund (vas haciendo) instead of andas haciendo here?

Not really, because they convey different feelings. Ir + gerund implies a gradual process moving forward step-by-step or towards a specific goal (like "little by little"). Andar + gerund, as used here, lacks that sense of clear direction. Digging a moat with a rake is being framed as a messy, aimless, or bizarre ongoing activity, which is exactly the vibe andar provides.

I know rastrillo means "rake" here, but doesn't it mean something else in Latin America?