1)Lender will not leave a positive trust until it exceeds certain amt. [like I will not give a positive feedback if amount is >0.5BTC (example)]
Different people have varying degrees of what they think "trustworthy" is.
2)Lender will not leave a positive trust until it exceeds certain interest (in percentage% or any amt) [like I will not give a positive feedback if interest amount is >15% or 0.025BTC (example)]
Basically, being greedy and making people pay extra to get some positive feedback (or you could think of it as bribing, but that's probably stretching it)
3)Also lender will give a positive feedback after some successive loan requests [like X giving a positive feedback after 5-6 successful lending transactions]
See my first response.