Hm, that could well be that their reputation lost something in the run of their 500 years of existence. But in 1529 they were still in their "younger" years considering that they came up around I think it was 1350-1400 and lasted well into the 1800s. What I know is, that the Janissary where short before revolting in 1529 while besieging Vienna because everything went wrong, it was cold and very heavy rain set in and almost no food to eat, they couldn't get through the walls although they were already breached, illnesses and diverse other things created a very bad morale amongst them (and there was no tavern lady around to raise the morale
). So Sultan Suleyman I. and his Pasha (something??) who by the way made his way up to the army commander by himself being a Janissary first of I think it was Albanian origin (a perfect example that everyone from everywhere could make a career in the Ottoman Empire; but I think he lost his head because of the failed siege), paid extensively high bonuses for the last charge and offered the first man to climb the walls a fortune. He made the promise to his soldiers that if that last charge had no success they would immediately return back home. But that last charge was also repulsed by the Landsknecht mercenaries. And so the Sultan kept his word and they left. And to be honest, they were very lucky that HRE was at war with France in 1529 because if the HRE army had additionally shown up at the siege scene (the 20,000 Landsknechte defending Vienna were just the "back-up emergency kit" in case of... and not the real HRE army) I don't think that anyone of the Ottomans would have made it home. As well as the people in Vienna were very lucky as this was probably one of the worst weathers during an autumn in all of the 1500s. Many of the Ottoman soldiers and other people accompanying them starved, died because of illnesses or simply freezed to death on their dreadful march back home.