I have a window A/C unit and I can't stand the way it looks outside.

I would paint it and the aluminum insulation to match my mobile home so it would not stand out.

maybe this will help...

Fix up a trellis around it (not too close) and grow stuff up it. OR Buy the expanding trellis fence that has artificial foliage on it and use that for an instant cure...........

Avoid painting ac units. The paint can hold in heat especially if you get it on the fins. Some people use the top as a shelf to decorate while others use the art of diversion to draw eyes away from the offensive looking unit. Most people ignore them much like the rusty tailpipe of a car. It’s just a mechanically nessesary item after all

Build a little arbor with lattice and plant clematis on it

this should give you some ideas. https://www.pinterest.com/pin/295689531758000983/

Don’t block the airflow or you’ll kill your air conditioner. But a fast growing vinelike morning glories on a vinyl fence can hide it. Make sure your arbor/fence is strong enough and high enough to hold your plant.