Just caught a crawl attempt from CODERO IPs.
Requests are made from several IPs, 1 second interval.
With the Same UA: User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:14.0) Gecko/20100101 Firefox/14.0.1
No supporting files, no robots.txt.
Now the interesting part, all IPs when visited redirect to the same shopping site(dudool). The crawler excepts and keeps http Cookie, passes it back on the next visit and provides valid site referrers.
But the bot runner still does not know that his crawler spits out headers that are not humanly possible, all though it really looks like a human visit when looking at the headers.