Two readings, two different words. Third-tone 倒 gives this one: to fall over, or to be bowled over by someone. Fourth-tone 倒 gives qīngdào, to dump or pour out, the reading in 倾倒垃圾, to dump rubbish.
usage
The admire sense belongs to written language. 令人倾倒 describes an audience won over by talent or beauty, and it is usually flattery rather than plain description. The literal sense stays physical: a wall, a tree or a stack of crates falls over.
