No flak from me. Mine came on to clean grass here too, and at Longcarse. They were wormed prior to arrival. I do a faecal worm egg count in April and October with a mixed dung sample - last year both tests showed no worm eggs, so I didn't worm. The two lambs we had killed had healthy livers - I asked the butcher for a report. I plan to graze them in a rotation with the heifers and the ponies.
I had one with a dirty bum and I took a faecal sample specifically from her but she was clear - I think she had ODd on the sugary lick

I will give them a flukicide as they move from the lambing shed to a clean field with their new lambs, as some of our land is wet, but won't dose again unless the faecal sample shows a problem.
I agree we're too reliant on chemicals. We've been spun a line by the manufacturers that we have to dose or we're bad stockmen, so we've become scared not to dose for everything. Before I bought my first sheep, I looked through the "Scottish Farmer" and scared myself silly with all the chemicals available and consequently, all the things my sheep would die from if I didn't dose them. I spoke to my vet about my concerns and he was of the opinion that if you ain't got a problem, don't treat it. My new vet is of the same mind.
I absolutely agree with VSS - make a friend of your vet; ours has been invaluable.