Good
Museum of Witchcraft in Boscastle it's widely advertised, but a lot of people are turned away by ticket price (£5) and how small the place looks.
I've been to Boscastle a fair over the years, but never bothered going in due to the cost, size and how few people seem to go in.
However last time I was there I had an hour to kill and thought fuck it why not.
Damn the place is like a Tardis of weird and wonderful stuff.
I spend about 2 hours in there and could have happily spent a full day looking at everything, reading all the cards and opening all the old school museum drawers filled with more items.

Holsworthy Museum
I was passing by and noticed the small town had a museum so thought it's free why not.
For a town with a population of less then 3 thousand it's a damn good museum.

Hexham, I was told it was a shit-hole and not to bother going....
The abbey is amazing (they let you go into the crypt which is cool) as is the town centre.
The town reminds me of York only less touristy and with better and cheaper parking.
Also has a surprisingly good Mexican.

Bad

Blackpool, it's filled with stag/hen parties and old people reminiscing.

Rhyl, a shitter welsh version of Blackpool

Ilfracombe, it's touristy as hell, there are nicer places with more to see nearby I just don't get it.

Plymouth Hoe, why the hell is it even classed as a tourist attraction.

Looe, honestly it used to be nice about 10-15 years ago then it got super popular with tourists and place is just terrible now, plus Nelson the seal died.

Clovelly, rip off to get in, it's not easy to walk down (wheelchairs and pushchairs are death traps) and there isn't much there.
The harbour is good and does get the occasional harbour porpoise but not worth £7 a head.