If you pay a rapper for a verse and they wack, its aiight as long as YOU'RE not wack. If everything else is good and people look at the song for the feature, chances are they'll hear you and like what they hear. On the other hand, a big feature doesn't guarantee spins, downloads or more importantly buzz around you and the song. I know some cats that got a Kendrick feature just before Kendrick became hot and it still hasn't done anything for them; all together, the song only has around 6000 views on youtube and it isn't anywhere else. With that being said, before getting a bigger name to feature on your song, you should ask yourself "what is this adding to my song/album artistically?" If an artist isn't bringing more to the table than their brand, you're probably wasting your time, effort and resources tryna get them on the track. This is part of organically collaborating which should be ideal for every artist. Oh, and if you can meet with them in person before they lay the verse or get in the studio with'em while they're recording, things will probably be a little more organic and the final product might sound a little better
