Task: Summarization
Input (English): This is a great price, but every time I've bought these through Amazon, the bottles frequently have dark... "stuff" on the threads of the bottle when you open it.  I've never seen this when buying them from the local drugstore, so I worry that these are either old or maybe not authentic?  Can't say for sure of course.  They do have the desired effect, so I'm not complaining too much.  It's kind of gross sometimes though.
Output (English): Good price -- not clean...?