when their is an unhealthy emphasis on "material" things like "hey can i drive your car" (if they are going on a date or something requiring transportation and this is a CONSTANT request).
if his/her mate throws alot of subtle hints for "favors" either financial or in relation to material posession under the guise of "just joking" that may be taken as a hint.
if he/she gets the guilt trip when that material possession is not awarded, or is not awarded as often as the receiver would like.
things of that nature, i don't think it necessarily has to be a blatantly obvious request for money, clothes, gifts etc., but they could be building their way there...like soror said if it FEELS like it, in your gut, then you may be correct...