Unless you are a sport martial artist, you have been taught all of your martial art lift that haymakers ( and many times even hooks ) are inevitably bad. They are slow, easy to block, and generally are inaccurate, often resulting in damaged or broken hands.

But what of a Haymaker Palm strike?

Obviously, just wildly throwing any technique is bad mojo ( never strike unless you are sure you will hit ) but what about in a combo? Using a palm strike instead of a fist will take away the chances of you breaking your hand and you can still deliver plenty of force even to the skull should you miss. In the hands of a martial artist, the haymaker can come out of no where ( at the end of a combo, from a weird angle etc etc ), and has plenty of power due to our training in how to properly manage momentum and torque.

Is this a good idea? My main weapon of choice would still be a straight palm to the face or punch to the body of course, but maybe palm strike haymakers are something I should start training as a power blow.

What do you guys think? Also, are there any other otherwise bad street fighting tactics that a martial artists can turn good?
No no, If you hit with the palm heel it is not a slap. I've practiced slapping and hooking palms and there is a noticeable difference. You just have to hit with the right part just like any palm strike.

And yes hooks are quite good if done correctly. But after once breaking my hand while doing a straight punch after only miscalculating the trajectory and landing spot by an inch, I've learned just how weak the knuckles are. I know punches are GREAT if used correctly, but I wouldn't want to use a hooking punch than is even more imprecise than a straight punch.