I never aspirate when doing sub-q shots. I've personally never heard of anyone getting a infection from sub-q shots, but you should always play it safe and sainitize the area before the shot with some rubbing alcohol or something similiar..
no...fat is not vascular...the purpose of aspirating is so you are not injecting IV (intravenous) but there are no large veins in fat...I am only at like 10%bf....but i can still just keep it in the fat