I've noticed that when I grind mine up, a load of trich's will stick to the spikes (its metal and wood, cheap but it does the job). So yeah the potency will be affected, but unless you've got a massive grinder and grind like a 1/4 at a time then you're not even gonna notice it. Plus, if you scrape off all the trich's when they've built up (takes a while... both to build up and to scrape off), eventually you'll have a small amount of kif to add in the next joint to get uber blazed.