Seems less-than-respectable to me. One thing to be at one and just happen to see/meet someone, but to plan it out and stuff seems like it would fall under the category of taking advantage of a person - in this case their emotional state.
Along the lines of going after drunk chicks at a bar, but that's certainly not uncommon so...
I wouldn't feel right about it, fwiw, but I've not had any real luck in that department either so my advice needs to be taken with a grain of salt.