Especially when there's still a little 60 Hz ripple visible.
And when you still haven't solved the periodic pipette vibration that makes getting seals hard.
[Then after you write some schlock like this, you worry about what PLS thinks about it.]
In other news, I have discovered a couple things:
When there is 0.5 pA RMS noise on a well shielded headstage, cleaning where the holder attaches can do wonders. Isopropanol + canned air = 0.05 pA RMS.
When ultrasonic cleaners are used correctly, they kick total ass. If you have one, try the glass slide test. HOLYMOLYCOWTHATISCOOLANDSADLYMIGHTBETHEWEEK'SHIGHLIGHT!