I find flash particularly useful when using udyr and there happens to be an ashe kiting me. Love it when I bait them into a chase, flash in, stun and wail on them, hehehe. But nothing wrong with taking ghost, you just have to know when to make use of it.

I'd take ghost/flash on heimer. When your only escape ability is to throw a grenade at them and pray it comes in handy.

useless people are the ones that don't know how to play with ghost

I like ghost on my AP Yi. Helps me dive bomb ghost+ult for a DFG combo, get a kill and proceed to spam 1k damage Qs on the other team. Then....PENTAKILLLLLLLLLLLLLLLLLL.

Using ghost to get top 1 second faster is a total waste. (Unless you're Rammus with +5 boots and a couple of hastes from your team, I guess.)

Save ghost until after the Windmill fight, and use it to clean up all the half-health enemies trying to run away.

Only Clarity and Smite are useless in Dominion. Every other spell is perfectly viable, even if some are better than others (Exhaust, Ignite, Revive, Garrison).

Ghost is probably the best overall summoner spell since even if you can't find a "good" use for it, it at least increases your mobility. Other spells like Revive, Flash, etc might go all game without being used once.