I'm a and i like this girl alot, however my sister thinks she's ugly?

Sorry if i talk to much today, but I really like this girl, and i brought her home with me last night before we went out. My mom saw her and thought she looked cute and pretty. however my sister thought she looked ugly n look like a drug addict. It kind of upset me because of what my sister thinks of her. I really like her, and i think that she's beautiful and most of my friends thinks she's hot n pretty, and we look cute together. My sister never think anyone i dated were hot. I want her to like ppl i like... and what she thinks of her really bothers me... but i kno i still like her a lot... what can i do? Yesterday she looked kind of crappy because she was tired n she had to wait outside for her roomie to come home cuz she lost her keys, thats why we went back to my place.