Sure thing they like scammers! They are interested just in fees collecting and those fees they get from scammers too. If there is some mechanism that the fee for BTCjam will be subtracted only after successful repay, they'll act differently (and probably does not exist anymore).
Lending business is like so:
1) Start a new lending site.
2) Get a lot of scammers.
3) . . .
4) PROFIT!
That is what I feel. These lending sites just take too much work and effort to avoid the scammers for the meager gains you can make. Frankly I think BTCjam likes the scammers and they probably only really care about collecting their up-front loan fee. They sure don't make it easy for the lenders.