Hiya,
Am I right in thinking these pigs also have sticky ears ?
Were they wormed before you got them ?
If not, giving them a quick jab would be my first suggestion.
Had they been living inside or outside?
Ours sometimes get a bit grubby looking during the winter when they're inside, but a couple of days outside (or a quick wash with some tea tree or baby shampoo if you're impatient

) usually sees them looking much better

HTH