Depends on a few reasons:1st. Does your dishwasher have just 1 sprayer rack or several? Single sprayer racks are awful if you don#39;t habitually pre-wash your dishes (ie rinse etc). 2nd. Do you use a finishing agent like jetdry? 3rd. Some dishwashers have several settings for dish type. My most recent had several dish settings including a light rinse up to more or less pot scrubbing for dishes. This seemed to vary the length of the wash cycles and power of the jet sprays used.4th. Most spinach is served with a sauce of some sort...It could be the sauce residue that is causing it to stick.
it may have something to do with the high levels of oxalate (the same thing that makes your teeth feel funny after you eat it...). Honestly though, that#39;s weird.