Is there such a thing as a bad worm?

To answer the thread title; no, not really, they are all beneficial.

By Red wrigglers I assume you mean Eisenia fetida, which are really compost-dwellers. Leave them where they are as they won't do well in the soil
What is PT?

One can;t really ID a worm from a description but the soil environment will give pointers.
Where did you see these... on the surface of your raised beds or when digging/making planting holes?
At night / during the day?
What colour is the saddle(if developed)? If the saddle is not developed it is not a mature worm.
What is your soil surface like eg lots of leaf mould?

Not sure what you mean by normal earthworms.
Out of the compost and in the garden there are surface dwellers (epigeic) that eat humic materials eg leaf mould and other decaying material) on the surface , vertical burrowers (anecic) that tunnel up to take food down to eat eg lob worm Lumbricus terrestris and horizontal burrowers (endogeic) eg green worm, Allolobophora chlorotica that eat and refine soil.

Leave them where they are whatever species they are but use their absence or abundance as indicators to help your growing. Low counts can indicate low mineral content, low humus contect or that the soil is too acidic, (though some species are more acid tolerant than others. They will provide aeration for the soil, help break up any compaction, allow water percolation, refine the soil, neutralise the soil (pH) act as a nutrient transport.

If there are very low worm counts in PT (whatever that is) add humus or minerals if deficient, reduce acidity. That advice of course depends what a PT is.

Read up on the fasinating field of worms? There are only a couple of dozen species of earthworm (all in Lumbricidae family) common in the UK.
Much of gardening is from kingdoms other than plants.

Earthworm guide | OPAL

NZ Flatworms are the baddies.

Are they the ones that almost look like leaches??

Indeedy!

Someone said you gert white worms in acidic soil, could be worth checking the ph.s

The white ones in acidic soil tend to be very thin in comparison to red earthworms (my own experience here).

I assumed that PT was a polytunnel but could be wrong (I often am......).

I don't think that there is much point in moving the worms as they'll go where they want, if the conditions aren't right then they'll move anyway, the best thing to do is make the conditions hospitable by adding well rotted compost etc. Also, if the soil is good them you've probably got a lot more worms than you realise, they may just be deeper, just a thought.

If they don;t have developed saddles then those are immature worms. If they are mature then possibly A. calliginosa

Thanks for that. In that case if the soil isn't too acidic for worm communities adding surface partially decomposed leaves as a mulch would initially encourage both vertical tunnelers to come up for a feed and surface dwellers, as well as retaining soil moisture, buffering the soil temperature and inhibiting weeds and in the slightly longer term providing organic matter for the horizontal burrowers.
+1

And one probably wont see the nightcrawlers L terretris which are vertical burrowers, unless out at night.

Thanks - I didn't realise there was so much to know about worms! PT is polytunnel.............. I am loving this forum!