Is it permissible to pray alone, as a precaution and to avoid dispute, if the worshiper believes that the Imam's prayer is invalid for reasons he deems to invalidate prayer, such as his use of alcoholic perfumes or his failure to perform ablution after touching the male organ, while the Imam does not see it that way?

The prayer of the mentioned Imam and those praying behind him is valid according to the madhhab of many scholars. The correct view is that the Imam's error does not transfer to the follower. The Prophet, peace and blessings be upon him, said: "They pray for you; if they are correct, it is for you and for them, and if they err, it is for you and against them." The follower believes that the Imam has fulfilled his obligation and that Allah has forgiven him for any mistakes. If you can only find this Imam, then it is better to pray behind him, due to the consequence of praying alone, which involves abandoning a Sunnah. Avoiding disagreement is good, as long as it does not lead to contradicting the Sunnah.