So what if aliens bleed acid? We breathe acid, suckers! And we can prove it! And while we're doing that, we can show why soda is very mildly bad for you.
The infamous tooth experiment which is meant to demonstrate that a tooth put in soda will dissolve within a few days, is now known to be a myth. A tooth doesn't dissolve in soda. If it did drinking citrus juice or eating salad with vinaigrette would dissolve teeth much quicker, as they contain stronger acids.