As they say, there is always a room for improvement. How much ever carefully the thesis be developed, it is always advisable to proof read the text not just one but more times so as to ensure that the problems are eliminated at all levels.
Before the final submission, each paper should be edited very carefully. Some tips that may help to add quality to the research work are:
Keep aside sufficient time for proofreading: The schedule for research should be so planned that the research scholar must finish all work and keep aside sufficient time which is exclusive for the purpose of proofreading. Not just once but couple of times. This should be planned way before the submission deadline
Handle one grain at a time: There are many problems to deal with when proofreading and correcting thesis work and it is important that the researcher moves ahead step by step. Always begin with punctuation errors and then graduate to spelling errors and finally towards the structuring of the sentences
Extra caution with Names and Numeric: In all the places in the thesis where names or statistical figure have been incorporated, the researcher must be sure of the spellings and the figures. The same caution applies to facts and figures
Hard Copy proof reading: After have carefully gone through a soft copy, may be more than one it is still important to go through the proof reading process on a hard copy. There may be few mistakes that may get overlooked on the system but get noticed or come forth prominent on a print out
Read loudly: This is a technique not followed by many researchers but it is often a very useful technique. Reading out the thesis loudly helps to identify the mistakes that the eye may have overlooked. It is even better to ask another person to read it out to you, in intervals and as a listener you could concentrate on mistakes that may have not been noticed in proofreading
Make use of common sense along with logic: The computer only works on logic. It may help the researcher with spelling errors but the application of the word and its suitability is the decision and discretion of the researcher. The use of correct vocabulary is the skill of an experienced researcher and the scholar could seek professional advice for the same
Getting third person perspective: This is the last but a very important tip as a neutral opinion helps to get a holistic perspective to the thesis and helps to eliminate biases if any
I work as a professor in a college. I too generally advise students to keep some time for review of thesis. It can also be done in this way, that you get your thesis reviewed by your peer or your colleague, to understand the flow of your thesis is correct for a new reader or not. Along with that of-course, grammatical errors and mistakes in specific terms should also be taken care of.