I am doing some research of spam detection on Twitter where my program is dynamic enough which can built a tree of datastructure of metadata of user and his tweets just taking a parameter as Screen_name or Twitter id but collecting legitimate user name and spammer name is a manual task. (If there is any other  way please suggest me.)
Use of Stream API could help you. You can collect the real time information there and using some clustering algorithms and data mining techniques can solve it.
Is there any way to get current legitimate user list from Twitter in 5000 to 10000