This excellent advice comes from Bernard Magee in the Mr Bridge weekly bulletin
This a direct quote from his article but the examples following are mine.
"Whenever you think your side has a misfit (no eight-card fit in any suit), then you should slow the auction down. Quite often, if you can stop at the two level you might just end up with a positive score, whilst most pairs will be playing in 3NT going two or three off. It will often pay to take a point or two off when evaluating your hand, since the difficulties involved in the play of misfitting hands can result in at least one trick fewer".
North ♠ KQxxx ♥ AJx ♦ Qxxx ♣ J
South ♠ xx ♥ xxxx ♦ AK ♣ AQxxx
After 1 ♠ from North, 2 ♣ from South and a rebid of 2 ♦ from North,
South should realise that the hands aren't fitting together and bid a quiet 2NT which despite the total of 26 points will need a lot of luck to make.
Similarly North ♠ AQxxx ♥ AQxxx ♦ x ♣ xx
South ♠ x ♥
x ♦ AQxxxx ♣ AQxxx
After 1 ♠ from North, 2 ♦ from South and a rebid of 2 ♥ from North, South should once again realise that the hands aren't fitting together and bid 2NT which will be very tricky due to the lack of movement between hands