Brochas Daf Chof Hey amud aleph

Rav Yehuda said (where there is) possible excrement, it is forbidden (to recite Krias Shema or pray)...

Others say that Rav Yehuda said (where there is) possible excrement in a house, it is permissible (to recite Krias Shema or pray; but (where there is possible excrement in a) rubbish dump (one is) prohibited.

The Rashba holds that in the earlier case (the first half of the Brysa) he has identified a possible source of excrement, but has not bothered to check whether it is the offending substance or only cement/mud. In such a case were he to pray, he would be negligent and required to repeat his davening. 

By contrast, the second half of the Brysa, in the case of the house, were one to pray, one would have no obligation to repeat one's Shemone Esre, because the use of the word "permitted" ("muteres") indicates that one is not negligent in making the assumption that there is no excrement in the house.

He points us to an earlier Gemara on daf Chaf Beis (amud beis) where he makes the same distinction between a man who begins davening and then sees excrement opposite him. He walks forward four amos (so that he can no longer see the excrement) and, the Rashba rules, resumes davening where he left off. By contrast, one who davens in a place where there is a reasonable expectation that there may be excrement is guilty of failing to secure himself within a place which qualifies as  "your camp should be holy" (Devorim 23:15). His davening is therefore an "abomination" and he is required to repeat it.

Question: as I benched Kiddush Levana tonight near a skip filled with household rubbish, including (perhaps) nappies/diapers I wondered whether it was permissible to stand within four amos facing it. I stood at a greater distance with my back to it, but did I have to?  Have concluded that since I couldn't smell anything and most people wrap their soiled nappies, the skip had the status of the house brought as an example in today's daf, so probably OK even within the four amos!