Poor quality samples - is there a cure?

i would like to know what people use to get rid of the eggs & bacon in the background of there samples? I got a good bunch of samples from wavcentral and the quality of these are horrible but would be very good to use in a tune. I tried to get rid of the unwanted bits by using the "Noise" option plugin and EQ'd the dam thing to death. It still didnt sound just right, the sample sounded hollow and no good.

also, do you guys do all your Reverbing and Effects to your vocal riffs before you put it in Cubase or after you imported it?

bare with me, i will have more questions later.
thanks!