The phrase "passable impression" means being able to do something well enough to make others believe or think that you are capable, even if you are not the best at it. Full definition
BE: John had visions of sitting down with you to do the audio commentary for the show, and then he did what I'd say was a pretty passable impression of you... (bullzeye.com)
In Dynamic mode the MiTo does a more than passable impression of a hot hatch, but in Normal mode it's downright horrible. (carsuk.net)
Wait and see what happens with AS but he has all the necessary equipment to do a passable impression of SA. (justarsenal.com)