1) ASV scans, while part of PCI compliance, do not make you PCI compliant. You also need a valid SAQ or passing audit by an approved QSA, depending upon your volume.
2) I'm not aware of any PCI-approved logo or seal. In general, PCI compliance is a matter for direct relationships, e.g. you need to give your processor a copy of your scans and your SAQ or your AOC and ROC. You can look up your processor in the Service Provider Listing. Seals don't mean anything because anyone can put them up.
- ASV - Approved Scanning Vendor
- QSA - Qualified Security Assessor
- SAQ - Self Assessment Questionnaire
- AOC - Attestation of Compliance, what your QSA gives you.
- ROC - Report on Compliance, what your QSA gives you.