taxing lanes is a bit annyoing as laner, but not realy bad for the team,
killstealing is a term i don'T like, rather a kill on the jungler than a enemy flashing away with 5 hp, and usually it's good to have early kills on ur jungler, as a fed jungler can snowball all lanes and secure dragon.
Not ganking at all is bad, but is usually means u got atleast a farmed jungler that evt can counterjungle, secure objektives.
Ganking at the wrong time is the worst possible thing, as it usually sets the jungler behind while also loosing the lane, and at the same time it's the hardest to avoid thing as it needs good warding in the enemy jungler to predict counterganks, as also a good awareness of the state of ur lanes ot not run into a fed enemy laner with not to much health, or bateing ur own laner in a risky battle.
The worst possible thing that can happen on a failed gank is a doublekill for the enemy lane, giving double buff to him.
At least on top that means usually ur laner can't leave the tower and in many matchups he will probably still die under his tower, as 2 early kills+double buff is a enormous advatage on top.