Question: Is everyone who has attended some lessons of certain Salafī scholars considered to be praised/commended (i.e. having a tazkiyah)?
Answer: Such questions should not be asked! What truly praises a person is his actions, his steadfastness upon the Sunnah, his adherence to it, his support of it, his holding firmly to it, his da‘wah towards it, and his implementation of it in word, deed, action, and belief. This is what benefits him. His adherence to the scholars of the pure Sunnah—without deviating from their path, opposing them, or standing against them, and so on—that is what praises him!
So if, in addition to this, some people of knowledge praise (endorse or recommend) him based on what they know of his condition—and the reality may not be as such—even if you brought tazkiyāt (commendations, endorsements) from the earth up to the seventh heaven, of commendations and writings, yet your actions are contrary to the truth and the Sunnah, then these writings and letters will not benefit you, nor will the flattery through which you gathered these commendations!
What truly praises (commends) a person is his deeds. This is not to diminish the value of scholars' commendations and praises—never! Rather, a person is called to live up to the commendation or praise given by someone from the people of knowledge and pure Sunnah. He must be worthy of this commendation (tazkiyah), act according to its implications, and be sincere & truthful in it. If such commendation (tazkiyah) comes, then rejoice and be grateful; if it doesn't, one should not grieve over its absence! May Allāh bless you.
This is what you should be asking about, for half of fiqh (understanding) lies in the question itself. May Allāh bless you.