I could see the lad walking toward me at the corner of my eye (put off already) with them famous words “can I help you”
This is reasonable, attentive and helpful staff member offering a friendly greeting
but this…
when I said ” no thank you I’m just looking” he proceeded to follow me around looking over my shoulder all the time
is less so, transitions quickly to pushy and overbearing sales spiel.
Regarding your comment about only just walking through the door, well that’s all well and good, you know you went in there to look, he didn’t know that, for all he knew you could have been looking for something specific, and had you been left to wander aimlessly unattended getting annoyed that nobody offered to help you.
Some staff are way too pushy, others way too inattentive, either way, the only way the shop manager/owner can improve is with feedback.