Yeah, that commands outputs all text to stderr (for no reason, should rather do it to stdout instead), so you need to run something like:
chia plots check -l -n 1 2> file.txt
The plot check is rather a useless command. It does a check using always 0 for the seed. If you re-run the check with a different seed (using the same starting point and the same number of tests) you will get different results.
So, the only reason to run it is with a minimal number of tests (6, I think), just to check whether the plot is busted or not. Also, if you have a bad cluster under a plot, this check will rather not catch it, so you would need to complement it with chkdsk / fsck test.
Also, there is an ‘-l’ option that checks for duplicates, although it only checks the local plots (so basically useless if duplicates are across different harvesters). The second problem with this option is that once it finishes checking for duplicates, it proceeds to do plots checks, so it is better to monitor it to stop that lengthy process, and also narrow the number of checks in case you want to run it unattended.