Internships in DC, especially in the thinktanks, are generally unpaid. DC shouldn't be attracting all these climbers in the first place, but like that bank robber of old, they go there because that's where the money is.
I graduated from college in 1980, and a dozen graduates from said college (counting just the ones I knew) ended up as interns on the hill.
Some sincere, some clymers, and I'm sure more than a couple of them were doing the horizontal mambo with a congresscritter.
This is neither a partisan or clinton induced issue. Has ever been thus, and likely will not change.