Sholkas 45-50 in the 2nd Adhyaya of Sambhav Khand which is part of Shiv Rahasya Khand of Sankara Samhita of Skanda MahaPurana, plainly state that the 10 Shaiva Puranas are Sattavik and 4 Vishnu Puranas are Tamasic.
दशशैव पुराणानि सात्विकानि विदुर्भुदः
वैष्णवानि च चत्वारि तामसानि मुनिश्वरः।
Moreover it seems Shiva Puranas are for Brahmins only but Vaishnava Puranas are not. The full verses are below:
This is for purely unbiased debate about Hindu scripture, not to put anyone down.
Are these considered spiritually harmful for Brahmins or lead to hell?