Glitch capture is usually a feature fitted to scopes with small buffer memories. The Fluke only has a few K of memory (varies with model) which means it can not sample for long time periods and keep all the samples without filling up the memory. To allow you to capture at longer timebases without missing glitches / spikes and high frequency noise it runs the ADC at high speed and keeps only the highest and lowest values. If you turn off glitch capture it samples more slowly and misses high speed signals which has the effect of removing high frequency noise.
On the PicoScope you have 1000s of times more memory so this compromise is avoided as it can sample at its maximum sampling rate for long periods of time. If you see noise / hash its genuine noise being seen at the probe tips.
To get a "clean" signal click on the channel options button (eg the "A" icon with the down arrow for channel A) and enable the low pass filter option. You can set the filter to remove the unwanted noise, but still keep the signal you want to see.
If you are having any problems with getting this to work, upload a .psdata file here for us to check the settings.