HL1 Trace hull/line doesn't hit's entities with solid type SOLID_NOT or SOLID_TRIGGER ("func_ladder", "func_illusionary", ....), but the given function can hit all the entities, to filter them you should made your's filter or use given one, to check - is this entity should be checked for collision or not.
Example: The code below will pass only player entities.
Code:
TraceFilter_SkipClassName traceFilter ("player");
TraceHull (source, destination, point_hull, traceFilter, traceResult);
Sorry for bad english...........................................