We have to realistically size people and situations up to function in the world - so an idealistic attempt to suspend this to think fluffy thoughts all of the time would just be naive foolishness.
What does matter is the amount of energy we put behind the thought - given enough repetition and 'shove' the pattern can become obsessive and very dangeorus to both the self and others. Not just energetically, but at all levels. To mind, body and spirit.
Quite a few end up with their life dominated by or even consumed by a mind monster created this way - leading to failing health and an inability to relate to others or to function in a balanced manner. Or worse...
Judging is for most of us a deeply conditioned habit (many from childhood try to make themselves feel better by putting down others and some families teach very bad habits in this and similar regards), although we vary enormously in terms of how often we indulge, what it takes to kick us off and how seriously we take our thoughts.
The fix is not to stop judging, but to over time develop enough self awareness that we immediately catch what we are doing - giving ourselves the chance to avoid being sucked into unconscious identification with the thought.
We in the beginning will without noticing find ourselves deeply caught up in this or indeed other habitual thought patterns (perhaps for hours) before we cop what is happening - but that's normal and OK.
The classic teaching is to register (sooner or later) when the thought arises, see it for what it is and just quietly set it aside. Not today thanks. To keep on doing this no matter what - even if we don't always catch the pattern immediately.
We train the body to stay physically healthy, but most fail to realise that the mind needs working with too.
Meditation is very helpful (essential?) because done correctly it's not about suppressing thought - it's about over time (not overnight) training the mind in the eventual ability to dispassionately observe thoughts as they arise - remaining easy with them no matter what.
It you could say builds a platform from which it becomes possible to observe our own ego mind in action.
Genuine self love (that's the enlightened variety - not self indulgence or the classic STS/service to self) is perhaps the fundamental ingredient in this, in that it's lack of care for the self that creates the need to compensate for what we mistakenly perceive as our own inadequacies in the first place. The tendency when trying to work an issue without self love is to tip into dissatisfaction with self and ultimately into anger and self loathing. It's hugely important no matter what that we be gentle with ourselves.
Good teaching (as is available from some of the spiritual traditions - some of the Buddhgist groups are very good/some less so) can also be very helpful because it can help us to see the ouselves and our actions and the surrounding realities in a more holistic and consequently more realistic and balanced sense - to recognise the cause of our itch (which can often be enough to release it), but to also realise that many suffer from these kinds of bothers.
When we over time reduce and eventually stop pouring energy into our ideations (actually energetic creations) the thought pattern (like any other habit) becomes weaker, fades and eventually disappears. Equanimity arises...
Wisdom/living wisely in manner that reduces hassle and stress is important too - another reason why teaching on how to live can be very helpful. This is the first level of self work in all valid traditions... The Dhammapada is a classic example of this:
http://buddhanet.net/pdf_file/scrndhamma.pdf
Mind is essentially self healing - given space it naturally sorts itself out.
Pouring in energy in an effort to suppress any of these sorts of thoughts is a mistake - it weakens the person while the ego feeds on this energy and uses it it to fight back/resist change - think the classic 'do gooder' scenario where the person ends up doing precisely what they have been preaching against. (clerical sex abuse is perhaps a case in point)
This broad approach is actually the basis for working with all of our 'stuff'. Some of the Buddhist traditions use the classic monk, elephant and monkey allegory to illustrate and teach the stages in the development of equanimity and an enlightened mind:
Shamatha Meditation Image - Art, Buddhism & Thangka Painting Courses by Carmen Mensink