Hermione pushed away his offering. If it was what she expected it was, she didn't want it. Sober-Up potion was vile and cheated her out of the temporary bliss of lowered inhibitions and fearless thoughts. She desired the oblivion that came with too much alcohol. Perhaps if she was lucky, she might even poison herself entirely or choke on her own vomit. At least then she wouldn't have to wake up the next morning to worry about how she was going to waste the rest of her meaningless life.