Some aircraft have strange spin characteriestics...
The Fokker Dr1 tends to just spiral if power is off (engine idle... NEVER stall a Dr1 dead-stick.), but with power, it spins like crazy.
The average trainer has to be forced to spin at all... and they don't continue spinning after you neutralize controls.
Fun-fly type models, after entering the spin, slowly reverse the ailerons, (as you get the feel for the technique, you can apply the reverse aileron faster) and the spin will flatten. If the CG is at the aft limit, some will climb while dong the flat spin at full power.

You should know the tall/spin characteristics of your aircraft. Practice with PLENTY of altitude, especially with flat spins. Remember that some panes can not recover from a spin if the engine dies...