If you can get a wax-specific iron for 99¢.....!!!!!! Then why bother with gran's iron?
Actually, you can do just fine with a clothes iron. If you see smoke coming from your wax as it hits the iron, it's too hot. Turn down, wait five minutes. As for wax in the holes, just turn it on the highest setting and let sit for a while: most of it will drip/smoke out.
That said, I doubt too many clothes irons can stay hot enough for CH4. If yours can, that's good.
But, a real waxing iron is be so much better. It really is. It stays hot, the temperature doesn't spike/drop, and you know you won't sear your bases.
If you're just starting out in tuning your own skis and don't want to spend a fortune up front, I'd start with wax (get the range), scraper, and brushes. Get a proper iron when you will have learned the limitations of a clothes iron.
I'm sure someone around here will be ready to sell you an iron