A quality is so far past good that any further praise would be redundant, and you want the verdict to say exactly that.
序 · The move
1State the stative verb (the quality) bare: 好, 棒, 漂亮.Is this a quality being rated to the top, not an action being timed or counted?
2Hang 得 straight off the quality, then drop in the whole 沒話說.Is 沒話說 left intact, with no 很/非常 pushed in front of the quality?
3Read it back: the quality is at its ceiling, praise exhausted.Does it mean 'too good to fault', not 'refusing to speak'? If it reads as literal silence, the slot is being misused.
例 · Examples
1他們家姊妹的感情the bond between them好得沒話說good past words — couldn't be better，幾乎從來沒有almost never once吵過架quarrelled (before)。
The sisters in their family get along beautifully — there's nothing to say but praise; they've almost never quarrelled.
Plain 得 takes any verdict the speaker builds (跑得很快, 寫得很漂亮). 沒話說 is frozen — it always means topped-out, beyond fault. One slot you fill freely; this one comes pre-filled.
極了 / 得不得了 / 得很 just push the quality to the extreme as a measure. 得沒話說 pushes it past the point where any words are worth adding — the praise itself runs dry, not only the degree.
沒話說 (literal: nothing to say in protest)
Standing alone, 沒話說 can mean a person has nothing to say back — silence, no comeback. Riding behind 得 on a quality, it is a verdict of praise: so good there is nothing left to add. The 得 in front flips silence into the highest mark.
他跑步得沒話說 → 他跑得快得沒話說 (the slot rates a quality at its ceiling, not a bare action; give it a 好/快 to top out)
這個地方很漂亮得沒話說 → 這個地方漂亮得沒話說 (no front booster; 得沒話說 already carries the extreme)
好得沒有話說 (padding the frozen phrase) → 好得沒話說 (the verdict sits whole, nothing inserted)
English folds the topping-out into the adjective up front ('couldn't be better', 'unbelievably good'). Learners reach for 非常/很 before the quality and never let the verdict ride behind it as a frozen tail.