Even if most ball python keepers still don’t call them hets, all pastels and probably all spiders are heterozygous for their respective mutations.

Many ball python keepers believe that 'het' means normal looking gene carrier but it just happens to work out that way with recessive mutations like albino which might have been their first exposure to the term. Heterozygous really means having an unmatched pair of genes for whatever mutation you are talking about. A pastel is a het because it has one pastel copy and one normal for pastel copy of the genes at the pastel locus. Until/unless a homozygous spider is proven it's a good bet that any spider you see also is heterozygous at the spider locus (one spider mutant copy and one normal for spider copy).

By understanding the true meaning of heterozygous and which morphs are heterozygous you can more easily predict the outcome of complex crosses like the one from this thread.