There's no easy way to tell how good a charger is just by looking at it. Generally you get what you pay for - if you order a "Genuine Apple iPhone OEM charger"

There's no easy way to tell how good a charger is just by looking at it. Generally you get what you pay for - if you order a "Genuine Apple iPhone OEM charger" on eBay sent from Hong Kong for $3, I guarantee you it will be a low-quality fake. But a $15 charger from a brand-name manufacturer should be reasonable quality. Fake chargers will copy the UL marks and labeling, so that doesn't help you. Of course, if it says "Designed by Abble" or "Designed by California", that's a pretty good indication of non-quality :-) (I've seen both of those on fake iPhone chargers - it should say "Designed by Apple in California".) The one thing people notice from bad chargers is their touchscreens malfunction when plugged into the charger. Bad chargers let through enough electrical noise to overwhelm the very small signals that touchscreens create. When you say your laptop gets a lot hotter at 110V, do you mean the charger or the laptop itself. Chargers are generally a bit more efficient at 240V than 110V, so I wouldn't be surprised if it is a bit hotter. But the output is exactly the same, so I wouldn't expect the laptop temperature to change. If it's hotter, I suspect ventilation is different or you happen to do CPU-intensive applications on planes.