For a beginner among other things it's advisable to see below the engine bay area while checking a vehicle for purchase. Any leaks can be observed and the owner may be inquired about that. As pointed out by @ dayrider, the owner should be able to give a technical reply on that, also what he had previously done to fix the leak (if at all).
An example of Solid axle suspension systems on Toyota vehicles can be given here (Land cruiser 60, 70 & 80 series). This suspension was designed to give more strength and flex to the vehicle, particularly for off roading purposes. But it sure comes with problems, specially failing axle and hub seals. The former shall result in differential oil leakage and the latter in axle grease leakage. The same goes for viper (namda) seals, whose failure can also cause axle grease leakage. So please don't hesitate to spoil your trousers and knees. Such leakages can cost around 20 k to fix and the agony of spending more than four hours at workshop. And mind it, we are talking about axles only, while there are many other suspension components to check for wear and tear e.g tie rods, control/radius arm bushings, sway bars and link bushings etc.
Also, do inspect shocks for leaks. Extra bouncing shocks are also a sign of having been worn out. New sets of Japanese ones are quite expensive. While kabli ones are usually unreliable. So there is no harm in getting down and dirty.
